Gunmen early this morning killed a U.S. citizen who apparently worked here trying to sell military patrol boats to the Salvadoran Navy.

It was unclear who murdered Peter Hascall, 35, or why. The prime suspects were two men who left his apartment with him at 2:45 a.m., about five minutes before he was killed in a nearby street by a single bullet in the chest, according to the Salvadoran judge handling the case. The two men have disappeared.

At the time of his murder Hascall was carrying two handguns, which was his usual practice, according to Judge Rosario Gochez and Margarita Galeas, who lived with Hascall.

Galeas said she believed Hascall carried the guns because he frequently traveled to El Salvador's eastern port of La Union, which is the base for the Navy and has been attacked by left-wing guerrillas. At La Union he spent a considerable amount of time with U.S. military advisers stationed there, she said.

A left-wing guerrilla radio station reported this morning that Hascall was a U.S. adviser, but this was denied by the U.S. Embassy and appeared to be untrue. The rebels' Radio Farabundo Marti did not discuss who had staged the killing and there were no immediate indications from either the judge or from Salvadoran police that the guerrillas were suspects.

The embassy said that Hascall did not work for it in any way. A U.S. official went so far as to say that "he was not a loose-cover spook," which is slang for a CIA agent working with diplomatic cover.

The Salvadoran armed forces' press office said Hascall once had worked for the Navy performing maintenance tasks but no longer did so.

Galeas and the embassy said that Hascall worked for Swiftships Inc., a shipbuilding company based in Morgan City, La.