Authorities in San Francisco are working to recover an AR-15 military-style rifle that was stolen from an unmarked police car over the weekend.

Police spokesperson Sgt. Michael Andraychak on Monday said that the semiautomatic assault rifle was stolen from the parked car while officers were conducting an investigation at a nearby location.

The department issues the rifles, which are similar to military M-16s, to certain specially-trained officers.

"An investigation is ongoing and no resource in being spared to recover the weapon," Andraychak insisted.

The spokesperson was not immediately aware of exactly when or where the weapon was stolen.

According to KGO, dispatchers broadcasted warnings to police every hour throughout Sunday to keep them on heightened alert over concern about the missing AR-15.

Watch this video from KGO, broadcast March 4, 2013.