Washington: The Pakistani-origin gunman who carried out the massacre of 14 people in California along with his Pakistani wife may have been radicalised as he was in touch with extremists, officials said on Friday, as an arms haul from their home indicated they were planning another attack.

Police said that while searching the apartment of the couple - Syed Rizwan Farook, 28, and his wife Tashfeen Malik, 27, - they found an armoury of weapons and explosives including a dozen pipe bombs and thousands of rounds of ammunition.