Los Angeles - Two rocket launchers turned into the Los Angeles Police Department as part of the city's gun buyback event appear to be antitank weapons from the military, experts said.

Police said the people turning them in at the buyback told officers they had family members who were at one time in the military and "they no longer wanted the launchers in their homes."

Several military experts said one of the weapons was probably a version of the AT4, an unguided antitank weapon. It's a single-shot weapon that a soldier fires and then discards the tubing.

The two launchers - long metal tubes that were once capable of propelling rocket grenades - were turned in along with 2,037 weapons at a gun buyback Wednesday, and exchanged for supermarket gift cards.

Detective Gus Villanueva said the launchers were "stripped-down shells" without the technical parts needed to discharge a projectile. Los Angeles police gun experts will be checking the origins of these weapons with the U.S. military to see if they were ever stolen, he said.

Among the 2,037 firearms were 75 assault weapons, officials said.

The gun buyback was moved up from its usual Mother's Day date in response to the massacre Dec. 14 that claimed the lives of 26 people, including 20 students at Sandy Hook Elementary School, in Newtown, Conn.

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