Police say they found a dozen pipe bombs and more than 3,000 rounds of ammunition at the home of the couple suspected of Wednesday’s mass shooting in southern California.
San Bernardino Police Chief Jarrod Burguan said a search of Syed Rizwan Farook and Tashfeen Malik’s house also found tools that could be used to construct improvised explosive devices.
He said the couple had sprayed between 65 and 75 rounds on Wednesday morning at a social services centre in San Bernardino, killing 14 people and injuring 21 others.
They left behind three pipe bombs which were designed to be operated by a toy car remote control, but didn’t work.
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The suspects fired another 76 rounds at police who pursued them in a car chase following the massacre.
Farook, 28, and Malik, 27, had more than 1,600 bullets with them when they were gunned down in their SUV.
Two police officers were injured, one of whom was shot in the leg and another who was hurt by flying glass.
David Bowdich, assistant director of FBI Los Angeles office, would not comment explicitly on reports that Farook had been radicalised.
He told journalists: “There was obviously a mission here. We do not know why.”
Mr Bowdich said there was “some level of sophistication” in the pipe bombs. He confirmed they were looking into whether the couple had learned to make the devices from an article in al Qaeda magazine, Inspire.