(CNN) -- A 23-year-old gunman killed two co-workers Friday at a Pathmark supermarket in Old Bridge, New Jersey, and then shot himself to death, Middlesex County Prosecutor Bruce J. Kaplan said.
The shooter wielded an AK-47 assault rifle and a handgun, and was carrying multiple ammunition magazines, he said.
"I believe everyone in the store was a target," said Kaplan, who said the gunman fired 16 rounds.
The man killed an 18-year-old woman and a 24-year-old man, and may have opened fire as he walked into the store, he said.
There were between 12 and 14 night shift workers in the store, Kaplan added. The man opened fire around 4 a.m.
CNN affiliate WABC broadcast aerial footage of at least three police cruisers in front of the supermarket, while several people gathered outside an adjacent restaurant.
NJ Transit reported that parking lots for its buses remain closed on the northbound side of route 9 in Old Bridge because of police activity.
Old Bridge is in central New Jersey, roughly 30 miles south of Newark.