WACO, Texas (AP) — Authorities say the nine people killed in a shootout at a Texas restaurant were all members of rival biker gangs that had gathered for a meeting.

Waco police Sgt. W. Patrick Swanton says 18 other gang members were taken to hospitals Sunday for injuries suffered in the violence at a restaurant shortly after noon.

Swanton says the gangs had arranged to meet to discuss differences when a fistfight began and quickly escalated to include knives and firearms. He says there were "hundreds" of gang members and a small number of other patrons in the restaurant.

Swanton says as many as five rival gangs attended the gathering. He says past tensions among the groups have focused on turf and recruitment efforts.

Authorities were investigating the scene and questioning witnesses Sunday evening.