LOUISVILLE, Ky. (WDRB/AP) -- Police said Thursday afternoon that they found 12 pipe bombs and hundreds of tools that could be used to make improvised explosive devices in the home of the couple responsible for a mass shooting. 

San Bernardino Police Chief Jarrod Burguan said in a press conference that Syed Farook and his wife killed 14 people Wednesday afternoon at a social services center and that the number of those wounded has risen from 17 to 21 people. 

Investigators will begin releasing the names of those killed Thursday after they notify the family members of those victims. As of 1:00 p.m. Thursday, police said most the identifications had been made. 

Police said Farook was at a holiday party for his workplace when there was an argument. He left and returned with his wife, Tashfeen Malik. Police say both of them were heavily armed and opened fire.  The chief says the attackers fired between 65 and 75 rounds at the center. They later died in a gun battle with police.

Chief Burguan said the two shooters left a device behind at the social services center. The device consisted of three connected pipe bombs with a remote control that apparently did not work.   

David Bowdich, the Assistant Director of the FBI, also spoke at the press conference. He said the FBI is now handling the case and is trying to determine if it is related to terrorism or not. 

"We know there was some international travel," he said. "They both came into the U.S. in July 2014." 

When asked if the international travel was connected to the shootings, he said "we do not know." 

Police said the SUV the couple was driving was rented. Chief Burguan also said the four guns used in the mass shooting had been legally purchased and that the pair, as far as police know, did not have a criminal record. 

Farook and his wife had a six-month-old daughter. Police said it is not yet clear who will get custody of that infant.  

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