At least three people have died in a multiple shooting at a supermarket in the U.S. state of New Jersey.

According to local authorities, the shooting occurred inside a Pathmark supermarket in Old Bridge, a suburb about 40 km from the city of New York. Among the dead was an 18-year-old woman.

While another, a 23-year-old man, was believed to be the gunman. The motive behind the shooting and how the shooter was killed was not immediately clear. But local media reported that the suspect was a former Marine who worked at the supermarket.

He returned there in the early morning and killed two people with an AK-47 rifle and an automatic handgun. He then shot himself when confronted by police.