A retired police officer working as a security guard at a northern New Jersey UPS facility shot shot and critically wounded an armed man who was walking toward him, authorities said.

Two men armed with handguns were in a white pickup truck that pulled up to the guard's vehicle at about 4:30 a.m. Saturday, Newark police said. One person got out of the pickup and approached the guard, who shot the person several times.

The other person in the pickup drove off immediately after the shooting and remains at large, police said. It wasn't known if that person was also wounded.

The guard, a former Union City police officer whose name was not released, was not injured.

No charges have been filed, but an investigation is ongoing.