WACO, Texas — Prosecutors have dismissed 15 more cases relating to the 2015 shootout in Waco involving rival biker gangs that left nine dead and 20 others injured.

McLennan County prosecutors said Thursday they're dismissing the cases while focusing on others with "a higher level of culpability."

More than a dozen other cases were dismissed in February and officials said last week that only about 25 cases will be prosecuted out of the more than 150 people indicted on felony charges of engaging in organized criminal activity.

Police arrested 177 bikers following the mayhem at a Twin Peaks restaurant involving members of the Bandidos and Cossacks motorcycle clubs. Law enforcement officers monitoring the gathering also fired on the bikers.

Only one biker has ever been tried and it ended in a mistrial.