Obama says FBI taking over San Bernardino shooting investigation

President Obama said Thursday he was handing the San Bernardino massacre investigation over to the FBI.

"At this stage we do not yet know why this terrible event occurred," Obama said. "It is possible this was terrorist-related ... it is possible this was workplace-related."

But, the president said, "at this point, this is now a FBI investigation."

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"We are going to get to the bottom of this," he said. "There may be mixed motives in all of this."

Obama, who has called for stricter gun control after other mass shootings, did so again on Thursday.

"We need to make sure when individuals decide they want to do harm we make it harder because right now it's just too easy," he said. "We're going to have to I think search ourselves as a society to make sure that we take some basic steps that make it harder — not impossible — but harder for individuals to get access to weapons.

After Obama finished speaking, he officially ordered that all flags be flown at half-staff at the White House and at all federal government buildings, U.S. embassies, and military installations in memory of the victims of the mass shooting at the Inland Regional Center.

The FBI was on the scene Wednesday shortly after a heavily-armed couple barged into a conference room where a holiday party was underway and opened fire, killing 14 and wounding 17 more. They were later killed in a hail of police bullets.

This article originally appeared on NBCNews.com.