U.S. Ambassador John Kelly's car was hit with one bullet during a brief exchange of gunfire between his bodyguards and a Christian militia patrol in east Beirut on Thursday, police reported.

A U.S. Embassy spokesman, who spoke on condition of anonymity, said: "The ambassador and all his escorts are fine." He refused to elaborate.In another development, the Shiite Moslem Amal militia on Thursday denied it has custody of three American professors and an Indian professor kidnapped in 1987.

A police spokesman, speaking on condition of anonymity in line with regulations, said one bullet hit the hood of Kelly's armor-plated dark blue Chevrolet in an "accidental exchange of automatic fire."

He said the gunfire occurred around noon when Kelly's Lebanese and American bodyguards in two escort cars fired in the air with automatic rifles "apparently to make way for the ambassador's convoy" in a traffic-jammed street in the Sin Fil neighborhood.

Kelly's motorcade was heading to the heavily guarded U.S. Embassy compound in the suburb of Aukar, north of Beirut.

The spokesman said a militia patrol from President Amin Gemayel's rightist Phalange Party, which was in the area, "opened fire in the air too in an effort to stop Kelly's convoy to check what was happening."

"Kelly's bodyguards fired three bullets at the Phalangists in a white Mercedes-Benz, and the patrol fired back. No casualties were reported among the Phalangist militiamen," he said.

"Kelly's car was hit with one bullet in the hood, and the convoy continued on its way to the embassy," the spokesman added. He did not elaborate.