BAYONNE - An explosion in Bayonne sent three PSEG contractors and two police officers to the hospital Wednesday morning.

A spokesperson for PSEG tells News 12 New Jersey that the contractors were testing a gas pipe with air while working on a new gas main they were installing on Chosin Few Way when the explosion happened. There was no natural gas in the pipe at the time, according to the spokesperson.

Bayonne police say that two of the workers were taken to Jersey City Medical Center. One of the workers injured is listed in critical condition. The other worker is in guarded condition. The third worker was treated for minor injuries.

Two police officers who were directing traffic at the time of the explosion were taken to Bayonne Medical Center as a precaution.

OSHA investigators are on the scene while they try to figure out what caused the explosion.