MANASSAS, Va. (WJLA) — Three people are in critical condition after a shooting Wednesday morning at a United Rentals facility in Manassas, Virginia.

Manassas City Police Chief Doug Keen said officers responded around 7 a.m. to multiple 911 calls reporting an active shooter at 9415 Wellington Road. Officers found three adult male victims, all employees of United Rentals.

Two were taken to UVA Prince William Medical Center, while the third was taken to Inova Fairfax Hospital, Keen said. All three were in critical condition.

Police identified a coworker, 37-year-old Marvin Grant, as the alleged gunman. He may be driving a gray Toyota Camry or Toyota Corolla with temporary North Carolina registration tags.

Police believe Grant left Northern Virginia and have issued a “be on the lookout” alert to agencies across the state. Investigators believe he may still be armed with a handgun, which was not recovered at the scene.

Anyone who sees Grant or the vehicle should not approach and should immediately call 911.

Police said the shooting was initially treated as an active shooter call but appears to have been workplace violence. Detectives are still investigating what led to the gunfire.

“Our working theory is that there was some kind of altercation that led to this,” Chief Keen said.

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Two of the victims were in the business’s garage or bay area, police said. The third came from an office area and entered the garage. Police are reviewing surveillance video from inside the facility.

Nearby schools were briefly placed on lockdown as officers responded. Those lockdowns have since been lifted, and Jennie Dean Elementary School has resumed normal operations, police said.

Residents are being told to stay indoors, secure their doors and avoid approaching the scene.