Speaking in the Oval Office on Thursday, he said it was possible the attack was workplace-related or that there were mixed motives.

Obama assured Americans that authorities would get to the bottom of what happened and called on people to wait for facts before making judgements.

He said many Americans felt there was nothing they could do about mass violence.

But, Obama added, “We all have a part to play”.

Obama said the nation must make it harder for people to carry out attacks. However, he acknowledged the threat couldn’t be eliminated completely.

The president said it was important for all Americans, including state legislators, to see what they could do.