California shooters had been radicalised 'for some time'

California shooters Syed Farook and Tashfeen Malik had been radicalised "for quite some time" before killing 14 people in San Bernadino last week, the FBI has revealed.

Both took part in target practice, on one occasion just days before the deadly attack on an office Christmas party.

FBI assistant director David Bowdich told a press conference that officers still did not know where or by who the pair were radicalised, but said they would "leave no stone unturned" in their bid to find out.

He also revealed that 19 pipes which could have been turned into pipe bombs were found at their home.

Mr Bowdich said the FBI had found "evidence of pre-planning" but it was not clear if anyone else was involved in that.

Farook and Malik were killed in a shoot-out with police following the attack.