"It is possible that this is terrorist-related, but we don't know. It's also possible this was workplace-related," he told reporters on Thursday at the White House.
"There may be mixed motives in all this, which makes the investigation more complicated. But rest assured, we will get to the bottom of this," Obama added.
On Wednesday, a couple armed with rifles and handguns attacked a center for people with developmental disabilities in San Bernardino, California, killing at least 14 people and wounding 17, the deadliest mass shooting in the United States in three years.
Syed Rizwan Farook, 28, and his wife, Tashfeen Malik, 27, were killed in a shootout with police after Wednesday's mass shooting.
Obama praised police and law enforcement officials for their professionalism in dealing with the situation but urged more efforts from all parties involved to curb the long-standing issue of gun violence in the country.
"We can't just leave it to our professionals to deal with the problem of these kinds of horrible killings. We all have a part to play," he said.
[caption id="" align="alignnone" width="650"]
US President Barack Obama speaks on US gun violence during a meeting with his national security team, at the White House in Washington, DC, December 3, 2015. (AFP photo)[/caption]During his remarks at the Oval Office, Obama was flanked by Vice President Joe Biden, Attorney General Loretta Lynch, FBI Director James Comey, National Security Adviser Susan Rice, who had just briefed the president on the shooting.
In another interview shortly after the shooting on Wednesday, Obama once again called for stricter gun control and said that mass shootings in America have no parallel across the globe.
"The one thing we do know is that we have a pattern now of mass shootings in this country that has no parallel anywhere else in the world," Obama said. "And there are some steps that we could take not to eliminate every one of these mass shootings but to improve the odds that they don't happen as frequently."
The mass shooting in California was the deadliest in the US since a gunman killed 20 children and six adults at the Sandy Hook Elementary School in Newtown, Connecticut, in December 2012.
There have been more than 350 mass shootings this year in the United States, in which four or more people were wounded or killed, according to the crowd-sourced website shootingtracker.com, which keeps a running tally of US gun violence.
By Press TV
