Live: Investigation into the San Bernardino mass shooting
Suspects left three pipe bombs attached to remote-control device at scene
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.