Investigators recover pipe bombs from Calif. shooting scene
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Police on Thursday said authorities had recovered a device containing three pipe bombs and a remote control that appears to have failed to detonate at the scene of the mass shooting in San Bernardino, Calif.
While searching a home linked to the killings, investigators also found 12 pipe-bomb-type devices as well as tools to make improvised explosive devices (IEDs) and thousands of rounds of ammunition, San Bernardino Police Chief Jarrod Burguan added.
About 300 local, state and federal law enforcement officers responded to the initial active shooter situation and crime scene, Burguan said.
Syed Farook, the male suspect in Wednesday's shooting that left 14 people dead and 21 injured, was in touch by phone and social media with more than one person under investigation for international terrorism, CNN reported.
Law enforcement sources told the network that it appears Farook was radicalized, contributing to his motive, while other factors such as workplace grievances could have played a role.
Farook traveled to Saudi Arabia twice, CNN reported, including in 2013 for the Muslim pilgrimage Hajj and eventually to pick up his fiancée.
Farook left a holiday party hosted by the county health department, reportedly after a dispute. He allegedly returned with his wife Tashfeen Malik and opened fire before fleeing the scene.
The armed suspects were later killed by police in a shootout where police said they fired 380 rounds while the suspects fired 76 rifle rounds.
"We cannot rule anything out at this point," David Bowdich, assistant director of the FBI field office in Los Angeles, said Thursday. 
"At the minimum, we have a domestic terrorism-type situation that occurred here," Burguan said Wednesday. "They came prepared to do what they did and they were on a mission."
Colleagues of Farook told the Los Angeles Times he was a devout Muslim, but rarely spoke of his faith in the workplace. 
President Obama said late Thursday morning that the shooting could be terrorism or could be something else, such as a workplace dispute.