(NBC NEWS) -- Grim details emerged Thursday about a massacre at a California holiday party that left 14 people dead and 21 more hurt, but investigators are still trying to answer the key question: Why?
The couple who unleashed the bloodbath Wednesday fired as many as 75 rounds at the Inland Regional Center in San Bernardino, and tried to slaughter more with a rigged pipe bomb that never detonated, authorities said Thursday.
American-born Syed Rizwan Farook, 28, and wife Tashfeen Malik, 27, were killed in a shootout with police more than four hours after the initial rampage. The couple — clad in black tactical gear but no bulletproof vests — fired another 76 rifle rounds during a pursuit with police, San Bernardino Police Chief Jarrod Burguan told reporters.
Authorities said they are still trying to determine why Farook and his wife attacked the party.
"We do not know the motive ... it would be irresponsible of me and be way too early to speculate on motive," said David Bowdich, the assistant director in charge of the FBI in Los Angeles.
"There was obviously a mission here," Bowdich said. "We do not know why. We do not know if this was the intended target or something triggered him."
Authorities told NBC News on Thursday that Farook appeared to have been radicalized. They said he had been in touch with people in the Los Angeles area who have expressed jihadist-oriented views.
Intelligence sources told NBC News that Farook appeared to have been in some form of communication with overseas individuals who are persons of interest to American authorities.
Farook and Malik had two assault rifles and two semi-automatic handguns that were legally purchased and registered, Burguan said.
In total, the pair had over 1,400 .223 caliber rounds available to them and over 200 9mm rounds on them during the gunbattle. The three pipe bombs were stitched together on a remote control car found at the scene, he added. A subsequent search of a home connected with the couple turned up 12 pipe bombs, Burguan said.
Farook had attended the Christmas party on Wednesday morning, but left about 15 to 30 minutes before the shooting began. Police said they received information by someone who was concerned about his behavior at the event.
Investigators say they know little about Malik or "where she is from."
Federal officials told NBC News that Farook traveled to Saudi Arabia two years ago. Authorities believe, based on the timing, that the trip was for the hajj, the pilgrimage that devout Muslims are required to do at one point in their lives. The officials believe Farook met Malik there, and then brought her back to the U.S.
