A law enforcement officer looks over the evidence near the remains of a SUV involved in the Wednesdays attack is shown in San Bernardino, California December 3, 2015. Authorities on Thursday were working to determine why a man and a woman opened fire at a holiday party of his co-workers in Southern California, killing 14 people and wounding 17 in an attack that appeared to have been planned. (REUTERS/Mario Anzuoni)
Authorities are continuing to search for a motive after a heavily-armed couple opened fire at an office holiday party in San Bernardino, Calif., on Wednesday, killing 14 people and wounding 21 others in one of the deadliest mass shootings in U.S. history. Follow Yahoo News' live blog for the latest information on the investigation.