Police are now searching for a black sport utility vehicle that fled the scene of a mass shooting that left up to 20 people injured inside of a San Bernardino, CA, social services office on Wednesday morning, federal law enforcement sources told the Los Angeles Times .

A San Bernardino police spokeswoman also confirmed there "are fatalities," but was unsure of how many people had been killed.

At least three suspected shooters fled the building after gunfire erupted, according to the sources, who requested anonymity because the investigation is active and ongoing.

It is unclear whether the people inside the vehicle are witnesses or suspects.

Police also used a robot to disrupt a "device" found inside the building, according to the sources, who added that investigators were assembling a battering ram to gain access to the office complex.

The San Bernardino Fire Department said the shooting took place in the 1300 block of Waterman Avenue, near Orange Show Road.

Sgt. Vicki Cervantes, the San Bernardino police spokeswoman, told reporters at the scene up to three shooters were reported inside the Inland Regional Center. Officers have not secured the building and are going door to door.

The suspects, she said, are heavily armed and were possibly wearing body armor.

FBI and ATF teams are on the scene.

The motive is currently unknown, but reportedly may be related to a party and awards ceremony being held for county employees.