WACO, Texas (AP) — Authorities are on guard in Waco after a shootout among rival motorcycle gangs at a restaurant left nine bikers dead and raised the specter of further violence.

Waco police Sgt. W. Patrick Swanton says authorities increased security to quell other possible attempts at criminal activity following the melee Sunday at Twin Peaks restaurant that also left 18 bikers wounded.

The violence erupted as members of at least five rival gangs gathered for a meeting.

Police say a dispute broke out, escalated to include knives and firearms and eventually spilled into the restaurant parking lot.

Parts of downtown were on lockdown Sunday night, and officials could be seen stopping and questioning motorcycle riders.

McLennan County Sheriff Parnell McNamara says the nine dead were members of the Bandidos or Cossacks gangs.