The crash happened at Bergenline Avenue and 30th Street in Union City just after 3 a.m.
Two EMTs who were in the ambulance were rushed to Jersey City Medical Center in stable condition, while two women in the Dodge Durango were taken to Hoboken Medical Center with injuries not believed to be life threatening.
Witnesses say the crash happened very quickly and that the sound of the two vehicles colliding was very loud.
The ambulance, out of West New York, was heading south on Bergenline Avenue with its lights and siren on, responding to a call for mutual aid. Somehow, the two women traveling east on 30th Street didn't hear or see the ambulance.
The collision was so violent that it flipped the ambulance onto its side. The SUV jumped the curb and ended up crashing into the front window of a pizza shop.
Emergency responders extricated the victims from the vehicles.
Bergenline Avenue was closed for cleanup and the investigation.