U.S. authorities look for militant links to shooters in California mass slaying

The couple suspected of killing 14 people at a holiday party in California amassed thousands of rounds of ammunition and a dozen pipe bombs, authorities said on Thursday as they sought clues to the pair's motives and whether they had links to Islamist militants.

Syed Rizwan Farook, 28, and Tashfeen Malik, 27, his wife and mother of his 6-month-old daughter, were killed in a shootout with police five hours after Wednesday's massacre at the Inland Regional Center social services agency in the city of San Bernardino.

Twenty-one people were wounded in the shooting, which ranks as the deadliest instance of U.S. gun violence in three years.

San Bernardino Police Chief Jarrod Burguan said at a Thursday news conference that the search of a townhouse leased by Farook and Malik in the nearby community of Redlands turned up flash drives, computers and cellphones.

Officials in Washington familiar with the investigation said so far there was no hard evidence of a direct connection between the shooters and any militant group abroad, but the electronics would be checked to see if the couple had been browsing on jihadist websites or social media.

One U.S. government source told Reuters that the FBI was examining information indicating that Farook had been in contact with individuals who were themselves under FBI investigation at some point, some from cases already closed. The source also said it was possible that one or more of the Farook contacts under scrutiny were located overseas.

But no information has yet emerged suggesting any ties or contacts between Farook and the Islamic State or other specific militant groups, the source said.

Officials from President Barack Obama to Police Chief Burguan said the attack may have been motivated by extremist ideology but that questions of motive remained unanswered.

"It is possible that this was terrorist-related. But we don't know," Obama told reporters. "It is also possible that this was workplace-related."

Farook, a U.S. citizen, was born in Illinois, the son of Pakistani immigrants, according to Hussam Ayloush, who heads the Los Angeles area chapter of the Muslim advocacy group Council on American-Islamic Relations (CAIR). Malik was born in Pakistan and lived in Saudi Arabia until they married, Ayloush said.

David Bowdich, FBI assistant director in Los Angeles, said Malik was admitted to the United State on a K-1 "fiancee visa" and was traveling on a Pakistani passport.

The couple entered the United States in July 2014 after a trip that included Pakistan, Bowdich said. Farook also visited Saudi Arabia for nine days in the summer of 2014, the kingdom's embassy in Washington said.

The director of the Islamic Center of Riverside, a mosque Farook attended regularly for two years until 2014, described him as a devout Muslim who made the pilgrimage to Mecca in Saudi Arabia a few years ago and celebrated his wedding reception at the mosque.

"His degree of faith is very high," the director, Mustafa Kuko, told Reuters. "He was a very quiet person, peaceful, never had an argument with anyone or a dispute."

Kuko said Farook attended morning and evening prayers from 2012 to 2014, when he stopped coming abruptly.

Farook, who according to Burguan had no criminal record, worked as an inspector for San Bernardino County Department of Environmental Health, the agency throwing the holiday party that came under attack.

Police cited witness accounts that Farook had been attending the celebration but stormed off in anger, then returned with Malik armed with assault gear and opened fire. Burguan said they sprayed the room with 65 to 70 rounds.