A witness who was at the site of the San Bernardino, California mass shooting -- which left at least 14 dead -- recorded cellphone video of local police descending on the Inland Regional Center with their guns drawn.
Dorothy Vong, a nurse at the facility for the developmentally disabled, told ABC News she thought she was witnessing an active shooting drill.
More than half a dozen police officers are seen entering the building.
Authorities confirmed that 14 died and another 17 were injured in the shooting. Police pursued what is believed to be the getaway car after witnesses said they saw the gunmen getting into a dark-colored SUV. The two suspects in the car -- a man and woman -- were killed at the scene after exchanging gunfire with police.
Officers are still investigating the center after they found a suspicious device they believe to be explosive, San Bernardino Chief Jarrod Burguan said.