Two US marines killed in Beirut

US marines in Beirut as part of the international peace-keeping force returned fire for the first time Monday after two marines were killed and seven wounded by heavy shelling in the worst violence seen in Beirut for a year.

As street battles and shellfire engulfed the city, the marines loosed an artillery salvo and fired a rocket from a Cobra helicopter gunship to silence their attackers, a US spokesman said. The marines, part of a four-nation peace force with French, Italian, and British units, were the first Americans killed in combat since US marines arrived in Beirut almost a year ago.

The 1,200 marines based at Beirut International Airport were caught in a crossfire between Lebanese Army units and Shiite gunmen entrenched in slum strongholds.

Meanwhile, President Reagan's special Middle East envoy, Robert McFarlane, arrived here from London for urgent talks with Wadih Haddad, Lebanese national security adviser, and Foreign Minister Elie Salem. After weekend meetings in Paris and London, McFarlane had said he thought prospects for peace in Lebanon were improved.

The fighting eased slightly after the marine response, and the embattled government of President Amin Gemayel ordered its Army to suspend operations shortly after midday. Maj. Bob Jordan, the US Marine spokesman, said the marines' response had helped quell the fighting.