UPDATE (6:45PM MT): Two dead, one male and one female. Explosives located inside SUV.

UPDATE (6:36PM MT): WATCH: San Bernardino PD Holding Press Conference on IRC Shooting.

UPDATE (5:13PM MT): San Bernardino deputy was injured in a shooting exchange with suspect; wounds are not believed to be life threatening.

UPDATE (5:05PM MT): Two suspects either in custody or dead, one suspect still at large.

UPDATE (4:30PM MT): One suspect dead, automobile shot up in San Bernardino.

WATCH LIVE (4:18PM MT): police are chasing suspect on foot in San Bernardino.

Tweets by SBC County Sheriff:

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Investigators do not know why as many as three men armed with assault rifles killed at least 14 people and wounded others at a state-run developmental center in San Bernardino, California, Wednesday.

Check our Active Shooter section for constantly updated content about the shooting and investigation.

San Bernardino Police Chief Jarrod Burguan said police were looking for as many as three shooters who "were on a mission" and "came in with a purpose."

The attack was at the conference center in the Inland Regional Center, where county health workers were reportedly holding a holiday party.

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