The FBI raided the home of a man believed to have bought the assault rifles used in the San Bernardino attacks

FBI investigators have raided the home of a man believed to have originally purchased the assault rifles used in the San Bernardino, California shooting that killed 14 people.

Early Saturday, authorities searched the home where the man was known to live

The news outlet cites law-enforcement officials who say they believe the man is a friend of Syed Farook, one of the two suspects involved in the Wednesday massacre.

Authorities say the man who is believed to have purchased the assault weapons is not considered a suspect in the shooting case.

The home that was searched is in Riverside, California — about 15 miles southwest of San Bernardino.

During the search, agents broke into a garage at the home and searched it using bomb-sniffing dogs. Two people, including the man's father, were briefly detained during the search, according to NBC News. The father reportedly said he did not know where his son was.

A law-enforcement official cited by The Associated Press says authorities haven't been able to talk to the man they say purchased the weapons "because he checked himself into a mental hospital after the attack."

Federal authorities cited by NBC News say "the two assault weapons were originally bought in 2011 and 2012," but it was unclear whether Farook gave money to the man to buy the weapons, or whether Farook bought the weapons from him at a later time.

FBI, left, and California Department of Motor Vehicles via APThis undated combination of photos provided by the FBI, left, and the California Department of Motor Vehicles shows Tashfeen Malik, left, and Syed Farook.

Officials have said Farook and his wife, Tashfeen Malik, were armed with four guns during the attack at the Inland Regional Center in San Bernardino: two semiautomatic handguns and two .223-caliber assault rifles, all of which were purchased legally.

In addition to the 14 people killed in the attack Wednesday, 21 others were wounded. Farook and Malik both died in a gunfight with police hours later. The FBI says it is investigating the massacre — the deadliest in the US since the Sandy Hook killings in 2012 — as an act of terrorism.