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Officials have told NBC News that it was likely a man called Syed Farooq and a woman, who one person described as his fiancee, were involved in the attack on a San Bernardino social services facility on Wednesday.
A third person who had been sought following the attack now appeared less likely to have been involved, the sources told NBC.
Up to three attackers opened fire at the Inland Regional Center facility, killing at least 14 people and wounding as many as 17, before fleeing the scene in a black SUV.
The hunt for the black SUV led police to an address in the neighboring town of Redlands, and police chased a vehicle that was seen leaving that address to travel back to San Bernardino. San Bernardino Police Chief Jarrod Burguan said the chase ended with officers engaging in a gun battle with a man and a woman, both of whom were armed with assault rifles and hand guns.The man and the woman were killed in the shootout.
A police officer was been injured in the gun fight but the injuries were not life threatening, the police chief said.
A third person was seen running from the vehicle and had been detained, Burguan said, adding in reference to the third person that "we do not know that they were involved" in the attack at the Inland Regional Center facility in San Bernardino.