(CNN) -- A 23-year-old gunman killed two co-workers early 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 added.
"I believe everyone in the store was a target," said Kaplan, who noted that the gunman fired 16 rounds during his attack.
The gunman killed an 18-year-old woman and a 24-year-old man, and may have opened fire just before he walked into the store, he said, citing broken glass in front.
There were between 12 and 14 night shift workers in the store, Kaplan said. 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.
"We are terribly saddened by the incident at our Old Bridge Pathmark store this morning," The Great Atlantic & Pacific Tea Co. said in a statement. "We express our deepest sympathies to the families of the victims and our appreciation to local law enforcement."
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.