SAN BERNARDINO, Calif. (CBSNewYork/AP) -- The two attackers who killed 14 people in a rampage at a social service center in San Bernardino fired as many as 75 rifle rounds at the scene, left behind three rigged-together pipe bombs with a remote-control device that apparently malfunctioned, and had over 1,600 more bullets with them when they were gunned down in their SUV, authorities said Thursday.
At their home, they had 12 pipe bombs, tools for making more such explosives, and more than 3,000 rounds of ammunition, Police Chief Jarrod Burguan said in a grim morning-after inventory that suggested Wednesday's bloodbath could have been far bloodier.
Photos surfaced Thursday of a yellow remote control car with a bomb that was left behind at the holiday party. Police say it was intended to be an ignition source and had wires and three pipes connected to it.
Another photo showed several pipe bombs in a duffel bag found at the suspects' home.
Wearing military-style gear and wielding assault rifles, Syed Rizwan Farook, a 28-year-old county restaurant inspector, and his wife, Tashfeen Malik, 27, slaughtered 14 people and wounded 21, up from 17, at the center shortly after he slipped away from an employee banquet he was attending there.
The couple was shot to death about four hours later and a few miles away in a furious gunbattle with police.
"There was obviously a mission here. We know that. We do not know why. We don't know if this was the intended target or if there was something that triggered him to do this immediately,'' said David Bowdich, assistant director of the FBI's Los Angeles office.
As CBS2's Danielle Nottingham reported, part of the plan involved three pipe bombs, tied to a remote control car. None of them exploded.
As the FBI took over the investigation, authorities were trying to learn why the couple left behind their 6-month-old daughter and went on the rampage.
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It was the nation's deadliest mass shooting since the attack at a school in Newtown, Connecticut three years ago that left 26 children and adults dead.
"We are mourning for the San Bernardino community, for the families who lost loved ones, and those with loved ones who've been victimized," said Connecticut Gov. Dannel P. Malloy in a statement, adding he called California Gov. Jerry Brown following the shooting. "Our thoughts are with the victims and their families on this day and the first responders and others who will be impacted by these events."
Malloy ordered enhanced patrols at state facilities in the wake of the shooting, WCBS 880's Paul Murnane reported.
At the White House, President Barack Obama said after meeting with his national security team that it was "possible this was terrorist-related'' but that authorities were unsure. He raised the possibility that it was a workplace dispute or that mixed motives were at play.
Police believe they acted alone in the attack. A third person who was detained near the site of the shooting may have nothing to do with the case.
CBS News has reported that Farook was in touch with people in the U.S. and overseas with suspected ties to terrorism.
Neither of the suspects was on a U.S. terror watch list.
The attackers invaded the center about 60 miles east of Los Angeles around 11 a.m., opening fire in a conference area where county health officials were having an employee banquet.
Farook attended the banquet, then left, then returned with murderous intent.
"They came prepared to do what they did, as if they were on a mission,'' Burguan said Wednesday.
Co-worker Patrick Baccari said he was sitting at the same table as Farook, who suddenly disappeared. Baccari said that when the shooting started, he took refuge in a bathroom and suffered minor wounds from shrapnel slicing through the wall.
The shooting lasted about five minutes, he said, and when he looked in the mirror he realized he was bleeding.
"If I hadn't been in the bathroom, I'd probably be laying dead on the floor,'' he said.
As CBS2's Danielle Nottingham reported, a law enforcement source said there were indications that the suspects shot management personnel first.
Chris Nwadike had been sitting at a table 5-feet away from Farook and stepped out of the room to use the bathroom.
"There's no way I can look at him and think he's attached to this until it happened, and it was him," Nwadike said.
Witnesses said the assault lasted nearly 5 minutes.
Farook was born in the U.S. to a Pakistani family, was raised in Southern California and had been a San Bernardino County employee for five years, according to authorities and acquaintances. Authorities said Malik came to the U.S. on a Pakistani passport in July 2014.
Baccari described Farook as reserved and said he showed no signs of unusual behavior. Earlier this year, he traveled to Saudi Arabia, was gone for about a month and returned with a wife, later growing a beard, Baccari said.
The couple dropped off their 6-month-old daughter with relatives Wednesday morning, saying they had a doctor's appointment, Hussam Ayloush, executive director of the Council on American-Islamic Relations, said after talking with family.
"We don't know the motives. Is it work, race-related? Is it mental illness? Is it extreme ideology? At this point, it's really unknown to us, and at this point it's too soon to speculate,'' Ayloush said.
Co-workers told the Los Angeles Times that Farook was a devout Muslim but didn't talk about religion at work.
Farhan Khan, who is married to Farook's sister, told reporters that he last spoke to his brother-in-law about a week ago. Khan condemned the violence and said he had "absolutely no idea'' why Farook would do such a thing.
About four hours after the morning carnage, police hunting for the killers riddled a black SUV with gunfire in a shootout 2 miles from the social services center in this Southern California city of 214,000 people.
Farook and Malik were found with assault rifles and semi-automatic handguns and were wearing "assault-style clothing'' with ammunition attached, authorities said.
Three explosive devices, all connected to one another, were found at the social services center, police said.
Federal authorities said the two assault rifles and two handguns used in the violence had been bought legally, but they did not say how and when they got into the attackers' hands.
New York Gov. Andrew Cuomo issued statement calling the shooting "an inexplicable tragedy."
"Congress must find the political will to act. Gun violence is an injustice against the American people, and Washington's failure to address it is appalling and inexcusable," he said. "New York State set the example after Sandy Hook by passing the strongest gun control law in the nation. We proved the possibility. Congress must do the same."
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