An assault weapon that was modified to fire fully automatically that was sold to undercover agents..Operation Sudden Impact solves six cold case murders, and leads to the arrest of forty gang members and associates who operated in Montebello, CA. .A large cache of assault weapons, many modified to fire fully automatically, were also seized. A rocket launcher was also seized by the joint task force. .Operation Sudden Impact was a multi agency effort of the ATF, Montebello PD, LA Co. Sheriff Dept, and the CA DOC, and was a two year long investigation.