The San Bernardino arsenal

Weapons confiscated from last Wednesday's attack in San Bernardino, California are shown in this San Bernardino County Sheriff Department handout photo from their Twitter account released to Reuters December 3, 2015. Police said the couple, Tashfeen Malik, 27, and her husband, Syed Rizwan Farook, 28, had two assault-style rifles, two semi-automatic handguns and 1,600 rounds of ammunition in their vehicle when they were killed. At the townhouse, police found another 4,500 rounds, 12 pipe bombs and bomb-making equipment. One bomb was rigged to a remote-control device. REUTERS/San Bernardino County Sheriffs Department/Handout

Ammunition confiscated from the attack in San Bernardino, California are shown in this San Bernardino County Sheriff Department handout photo from their Twitter account released to Reuters December 3, 2015. REUTERS/San Bernardino County Sheriffs Department/Handout

Weapons and other evidence are shown on a tarp near a SUV involved in the attack in San Bernardino, California December 3, 2015. REUTERS/Mario Anzuoni

Ammunition confiscated from the attack in San Bernardino, California are shown in this San Bernardino County Sheriff Department handout photo from their Twitter account released to Reuters December 3, 2015. REUTERS/San Bernardino County Sheriffs Department/Handout

The remains of a SUV involved in the attack is shown in San Bernardino, California December 3, 2015. REUTERS/Mario Anzuoni

FBI agents look over a vehicle in front of a residence in San Bernardino, California December 3, 2015. San Bernardino Police Chief Jarrod Burguan told a news conference the search of a townhouse leased by the two shooting suspects in the nearby community of Redlands turned up flash drives, computers and cell phones. REUTERS/Alex Gallardo

Law enforcement officers look over the evidence near the remains of a SUV involved in the attack in San Bernardino, California December 3, 2015. REUTERS/Mario Anzuoni

FBI agents search outside the residence that is in connection to the shootings in San Bernardino, California December 3, 2015. Officials in Washington familiar with the investigation said there was no hard evidence of a direct connection between the couple and any militant group abroad, but the electronics would be checked to see if the suspects had been browsing on jihadist websites or social media. REUTERS/Alex Gallardo

FBI investigators sort through contents of the garage of the suspects involved in the attack in Redlands, California December 3, 2015. At the townhouse, police found another 4,500 rounds, 12 pipe bombs and bomb-making equipment. One bomb was rigged to a remote-control device. REUTERS/Mario Anzuoni

A FBI investigator walks through the backyard at the townhouse of the suspects involved in the attack in Redlands, California December 3, 2015. The guns were legally purchased in the United States, said Meredith Davis, a spokeswoman for the Bureau of Alcohol, Tobacco, Firearms and Explosives. REUTERS/Mario Anzuoni

FBI investigators work near a car at the townhouse of the suspects involved in the Wednesdays attack in the aerial photo in Redlands, California December 3, 2015. San Bernardino Police Chief Jarrod Burguan said Farook bought the two handguns. The rifles were purchased by someone else, who Davis said was not linked to the investigation. REUTERS/Mario Anzuoni

A law enforcement vehicle that suffered damage from bullets is shown in this San Bernardino County Sheriff Department handout photo released on their Twitter account to Reuters December 3, 2015. REUTERS/San Bernardino County Sheriffs Department/Handout

The remains of a rented SUV involved in the attack is shown in San Bernardino, California December 3, 2015. REUTERS/Mario Anzuoni

A Sheriff's Office Crime Scene investigator unloads equipment at the scene of the investigation around an SUV in San Bernardino, California December 3, 2015. REUTERS/Mike Blake

FBI investigators sort through contents of the garage of the suspects involved in the attack in Redlands, California December 3, 2015. REUTERS/Mario Anzuoni

The remains of a SUV involved in the attack is shown in San Bernardino, California December 3, 2015. REUTERS/Mario Anzuoni