WHEN TOURISTS AND GUERRILLAS SHARE A TOWN

None of the tourists who arrived one recent morning at the town on the lake seemed to have any notion of what had happened here. What they saw were the bright colors of Indian clothing -- the men's trousers striped purple and white and the women's blouses embroidered with the figures of birds.

What they heard was the garbled Spanish with which the Indians bargain and the cries of Indian children demanding to be paid for having their photographs taken. Within an hour and a half, well before noon, the tourists were back on their boat and gone, unaware that this town on the beautiful lake had seen within recent months more than a half a dozen kidnappings and probable murders.

In the morning, it is the tourists who come to visit the town on the lake.

In the afternoon, the Army rumbles in.

At night, it's the turn of the guerrillas.

In the background, like a greek chorus murmuring their comments, are the town's Indian inhabitants.

Leftist guerrillas struggling for control of Guatemala, armed men preaching revolution, have been slipping into one of this Central American country's main tourist regions for the past year and a half. But unless the tourist speaks Spanish and asks questions, he or she is unlikely to notice any effect from the guerrilla intrusions. Guerrilla activity in this region is limited mostly to making propaganda.

But despite the low-key nature of this activity, it is considered significant that some of Guatemala's traditionally passive Indians are beginning to join, or at least support, guerrilla groups. The Indians make up about half of Guatemala's population of 7 million people. Guatemala, which is about the size of the state of Tennessee, is the most populous of the five Central American republics.

When Ronald Reagan was elected president of the United States last month, supporters of the Guatemalan government of Gen. Romeo Lucas Garcia burst into celebration. But if the Indian population ever became mobilized against the government, it is difficult to see what good outside aid from a Reagan administration could do to help that government.

Indian grievances against the ruling elite tend to focus on disputes over land, the exploitation of seasonal Indian laborers, and the conscription of Indian youths into the Army.

At Santiago Atitlan, the largest and most traditional of the towns on Lake Atitlan, a major tourist attraction, most of the inhabitants are Indian. The only outward sign of anything unusual is the occasional movement of a truckload of government troops in and out of the town. To the casual visitor, the inhabitants look cheerful and relatively satisfied. Questioning reveals that there is a high degree of malnutrition among the children, a condition common to the country's Indian population as a whole.

Aldous Huxley, the writer, is said to have remarked that Lake Atitlan is the most beautiful lake in the world. Surrounded by three volcanoes, cliffs, and terraced hillsides, the lake is indeed a spectacular sight. It is about 40 miles west of Guatemala City in a straight line, or double that distance if one takes the winding mountain roads. Most of the inhabitants are descendants of the Mayan Indians who lived in the region when the Spaniards arrived. The Spanish fought and won a major battle on the northern shore of the lake.

For the most part, the government troops stay away from Santiago Atitlan. Several hundred of them are stationed near the coffee trees a mile or two to the northeast of the town. They are said to be searching for the elusive guerrillas who have visited nearly all of the dozen lake towns over the past year or two. Before, the guerrillas focused on more-remote areas.

Last June, guerrillas belonging to one of Guatemala's oldest leftist organizations, the Organization of People in Arms, entered the town one night and held a propaganda meeting. The guerrillas, some of whom spoke the local Indian language, criticized the government, declared themselves friends of the people, and spoke of "liberating" the country.

By all accounts, it was a friendly affair. According to one version of what happened, the guerrillas bought soft drinks for the occasion. Another version has it that people did the buying and treated the guerrillas. Some of the people made the mistake of applauding the guerrillas, and this was apparently reported to the government authorities by informers in the town.

But retaliation against the town because of the friendliness it showed the guerrillas did not come until Oct. 22, when the Army sent troops into the area. Within a few weeks, at least half a dozen people were kidnapped from the town -- never to be seen again. Since the Army was in control of Santiago Atitlan at the time, it was presumed that if it did not direct the kidnappings, it at least condoned them.

But people are reluctant to talk about this.

"I could tell you many things that would shock you," one person with whom I spoke said. "But it would only get me into trouble. . . . There are informers everywhere."

"The best people are getting killed," the same person said, declining to elaborate on that remark.

"I hope you don't write anything that will get anyone killed," another said.

One recent day at about 5 o'clock, well after the tourists and their boat had left Santiago Atitlan, the Army made one of its appearances. A single truck rattled into the town, with soldiers standing uneasily in the back in camouflage uniforms. They pointed their rifles outward as though they might at any moment be attacked. Several soldiers took up positions in the town's main plaza. Within an hour or two they were gone.

"Why is the Army here?" I asked one of the town's many peddlers of tourist wares.

"I don't know," he replied. "They come every day."

Was he aware that some people were kidnapped and possibly killed after the Army arrived?

"Oh, yes. That's right. . . . But we don't know why it happened."

The first person to be kidnapped was the director of the local radio station, an educated Indian named Gaspar Culan Yataz. He had spoken on the radio about human rights. He was dragged bleeding from his home by unidentified armed men on the night of Oct. 24, two days after the Army arrived in the town. Witnesses said he put up quite a fight. His relatives assume that, as is the practice in many such cases in Guatemala, the radio director was first tortured and then killed. The station was closed.

Within three weeks at least six persons were kidnapped. One person, a student who fled to a town some distance from Santiago Atitlan, was tracked down and killed there.

For several weeks, hundreds of persons sought refuge each night in the town's Roman Catholic church, a huge white stone structure dating from the days of the Spanish Conquest. They were frightened by reports that the Army had a "hit list" with hundreds of names on it. At one point, as many as 600 of the town's 20,000 inhabitants were sleeping in the church each night.

A story began to circulate among the Indians that Maximon, a Mayan god much revered in Santiago Atitlan, was assuming the form of various animals at night and harassing the soldiers stationed near the town. According to the story, the soldiers would see Maximon only for an instant. He would disappear just as they fired their weapons. Maximon is most often depicted as a small man with a wooden face, booted feet, two felt hats on his head, a cigar stuck in his mouth, and many brilliantly colored scarves wrapped around his neck.

But little of this turmoil and myth is to be seen in the peaceful daytime of a tourist visit to Santiago Atitlan, and the inhabitants appear to be entering the modern world at a rapid rate.

An Indian peddler will sell you an oil painting of Maximon and assure you that almost everyone in the town still believe in the god. But at the same time , the salesman is quick to say that he accepts traveler's checks.

Santiago Atitlan wakes to the sound of transistor radios. But it is also alive with the old ways of doing things.

At 6:30 a.m., one sees men carrying sharp machetes and hatchets over stone-paved streets to work in the fields. Women wash clothes in the lake. Others carry babies slung on their backs as they shop. Men bent under heavy loads of firewood move at a trot. The load is supported by a sling placed around the forehead. The smell of fires fills the air.

Some of the women wear a long ribbon wrapped on their heads to form the characteristic halo-like headdress of Santiago Atitlan. It can be seen on Guatemala's 25-cent coins.

But writing about a year ago in the magazine Geo, Louis de la Haba, an anthropologist, indicated that all this is bound to change. He noted that near the town, an exclusive subdivision is being built with a clubhouse on the lakeshore and an airstrip close by.

The writer stated that the Indian peasants own less and less land and are becoming more and more dependent on wage labor. They are thus more subject to outside influences. He quoted another anthropologist as predicting that the Maximon cult -- and presumably many local customs -- will disappear within 6 to 10 years.

But for the moment, Santiago Atitlan is still a tourists' paradise. In the evening, when the sun sets over the lake and the clouds drift past the volcanoes , it is difficult to imagine that much will change. One would like to think that while the tourists, the Army, and the guerrillas come and go, the Indians will endure.