An unidentified man who shot and seriously wounded a U.S. sailor in downtown Hiroshima over the weekend also threatened two of his companions at gunpoint, police said Monday.

The three servicemen were walking in the downtown area after drinking at a nearby restaurant at around 4 a.m. Sunday when the gunman, who was driving a black car, fired a shot from the left front window, hitting Petty Officer 2nd Class Eric Heinz in the left side of his waist.

Heinz, 21, is a navy corpsman stationed at the U.S. Marine Corps base in Iwakuni, Yamaguchi Prefecture. It was initially reported he is a marine.

The gunman then got out of the vehicle and pointed the gun at the two other servicemen, who were trying to assist Heinz, and said something in Japanese like "I'll shoot you, too," police said. The weapon appeared to be a chrome-plated handgun.

Police are investigating the attempted murder and are searching for the gunman, who fled the scene. They are using footage obtained from security cameras positioned near the scene.

Police described the gunman as between 25 and 35 years old and about 165 cm tall. He wore white trousers and a black sweat shirt. Witnesses told police that he walked with a limp.