Anonymous gun buy back program

Guns sit on a table that were surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif. The San Francisco Police Department held a one-day gun buy back event that paid $200 per gun turned in. A better than expected crowd resulted in payback money running out and vouchers were issued to collect money within a week. Over 200 guns were collected.

A San Francisco police officer inspects a gun that is being surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

San Francisco police officers document guns that are being surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

San Francisco police officers inspect a gun that was surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

People wait in line to turn in firearms during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A stack of rifles is seen during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

San Francisco police officers document guns that are being surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A San Francisco police officer inspects a rifle that is being surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A San Francisco police officer documents a rifle that is being surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

San Francisco police officers inspect guns that are being turned in during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A San Francisco police officer adds a rifle to a stack of turned in guns during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A San Francisco police officer documents a rifle that is being surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A San Francisco police officer sits next to a stack of rifles during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

People wait in line to turn in firearms during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A San Francisco police officer inspects a gun that is being surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A San Francisco police officer documents a gun that is being surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

Guns sit in a box that were surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

People wait in line to turn in firearms during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

Guns sit in a box that were surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A San Francisco police officer inspects a rifle that is being surrendered during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

A San Francisco police officer adds a rifle to a stack of surrendered guns during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.

Bullets and a clip from a gun that was surrendered sit on a table during a gun buy back program on Dec. 15, 2012, in San Francisco, Calif.