Police in Texas have warned of revenge attacks from motorcycle gangs following the arrest of 170 people in connection with a shooting in Waco yesterday in which nine people died and 18 were injured.
All those arrested are being charged with "engaging in organised crime".
The incident took place outside the Twin Peaks Sports Bar and Grill at a shopping centre when a feud among rival biker gangs led to a gun battle.
Eighteen people were taken to various hospitals with injuries that included gunshots and stab wounds, said Waco Police Sergeant Patrick Swanton.
The fight, which involved members of at least three gangs, erupted shortly after noon local time and quickly escalated into a brawl involving clubs, knives and chains, Sgt Swanton said.
The fight may have been tied to a dispute over a parking spot, he added.
When the bikers began shooting, officers moved in, some of them also firing their weapons.
When the shooting ended, bodies were scattered across two car parks.
About 100 weapons were recovered from the crime scene, police said.
"These are very dangerous, hostile biker gangs," Sgt Swanton told reporters.
"A lot of innocent people could have been injured today."
There would likely have been more casualties, Sgt Swanton said, but police were on the scene when the fight erupted, anticipating "issues" with what he called "criminal" gangs.
Eight people were killed at the scene and one died in hospital. All of the fatalities were bikers, and no officers were hurt.
Sgt Swanton said police were frustrated with the management of Twin Peaks, a chain restaurant that bills itself as the "ultimate sports lodge" and said police had warned the bar that there might be trouble.
Jay Patel, Twin Peaks franchise operating partner, posted a statement on Facebook saying the company shared in the "community's trauma" and was cooperating with police.
