California shooting: Tom Ridge says 'I think this is terrorism'

America's former Secretary of Homeland Security says he is convinced the killings in San Bernardino were an act of terrorism.

Talking to the BBC's Katty Kay, Tom Ridge acknowledges that he's ahead of the White House and authorities in California in drawing that conclusion.

But he said the amount of weaponry and the pipe bombs found at the attackers' house made him confident of his conclusion.