SAN BERNARDINO, Calif. (TheBlaze/AP) -- The two attackers who killed 14 people in a rampage at a banquet 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.
SAN BERNARDINO, CA - DECEMBER 03: FBI agents and local law enforcement examine the crime scene where suspects of the Inland Regional Center were killed on December 3, 2015 in San Bernardino, California. Police continue to investigate a mass shooting at the Inland Regional Center in San Bernardino that left at least 14 people dead and another 17 injured. (Photo by Sean M. Haffey/Getty Images)
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.
Syed Rizwan Farook, a 28-year-old county restaurant inspector, and his wife or fiancee, Tashfeen Malik, 27, slaughtered 14 people and seriously wounded more than a dozen others in the attack at a social service center for the disabled after he slipped away from an employee banquet he was attending there. The couple were gunned down about hours later and a few miles away in a furious shootout with police.
San Bernardino Police Chief Jarrod Burguan revealed that Farook purchased two of the handguns used in the shooting legally but did not purchase the rifles, which were also purchased legally.
An FBI official said Malik was in the U.S. on a visa with a Pakistani passport and the couple recently traveled to Pakistan. Other reports have suggested they may have also traveled to Saudi Arabia.
Flowers sit on the sidewalk on Waterman Avenue near the Inland Regional Center on December 3, 2015 in San Bernardino, California. Police continue to investigate a mass shooting at the Inland Regional Center in San Bernardino that left at least 14 people dead and another 17 injured. (Photo by Justin Sullivan/Getty Images)
As the FBI took over the investigation, authorities Thursday were trying to learn why the couple left behind their 6-month-old daughter and went on the rampage - the nation's deadliest mass shooting since the Newtown, Connecticut, school tragedy three years ago that left 26 children and adults dead.
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.
Law enforcement experts said investigators may well conclude the killers had more than one motivation.