The chase began late Tuesday night, a Newark police spokesman said. The occupant was wanted in connection with an armed robbery.
Elizabeth and Hillside police picked up the chase when the vehicle crossed the border.
Police said that's when the Jeep hit an unmarked Union County Sheriff's Office vehicle, injuring a deputy. The deputy was taken to University Hospital in critical condition.
One occupant of the Jeep was apprehended.
No names have been released.