Police are investigating a mass shooting that left 14 people dead and 14 more wounded with what police called “significant injuries” on Wednesday morning in San Bernardino, California.

Police said at a news conference that up to three shooters reported to be heavily armed, prepared and dressed in tactical gear entered the Inland Regional Center, a facility for people with developmental disabilities, and opened fire. Those responsible fled the scene in a dark-colored SUV and were still at large as of Wednesday afternoon, police said.

According to KABC and many tweets by those on the ground, rescuers did not wait for ambulances and began loading the injured into trucks to get them to safety.

“They were being carried on trucks … They were shot, they were injured. Some of them did not survive,” said NBC Los Angeles reporter Tony Shin, describing victims he saw being brought to the triage area.

It is unclear how many people were at the facility at the time of the shooting. The center’s Facebook page says it employs nearly 670 staff members at its facilities in San Bernardino and Riverside counties, providing service to more than 30,200 people. The three-story building is still being cleared as SWAT members go through each office.

According to the Sheriff of San Bernardino County, most of the victims were in a central area of the building but cannot confirm where.

Schools are on lockdown and one elementary closest to the airport is being evacuated, according to NBC reporters. SWAT and multiple police are looking for the suspects who are still at large.