A brawl-turned-shootout between rival biker gangs left nine people dead and 18 injured outside a crowded sports bar in Waco, Texas.

Twin Peaks, the sports bar where the fighting erupted on Sunday, will be shut down by authorities for seven days, Waco police Sgt. Patrick Swanton told reporters.

Swanton said that 165 to 175 bikers were being booked into the county jail. Earlier, he gave a figure of 192. He said the charges could be upgraded, up to capital murder.

The rumble at Twin Peaks Sports Bar began at midday Sunday. Fighting spilled from the restaurant, first involving fists and feet but then chains, clubs and knives before gunfire erupted. The parking lot was left a blood-streaked battleground.

“It progressed very rapidly,” Swanton said. Police — who had been expecting trouble from the gathering — were on the scene when fighting broke out, and they quickly called in reinforcements.

“They started shooting at our officers, and our officers returned fire, taking several of them down,” Swanton said. “I’m amazed at the number of rounds fired.”

He said eight people died at the scene and another died in the hospital — all biker gang members. Eighteen people were taken to hospitals for gunshot and knife wounds, with some victims suffering from both.

“I’m amazed we did not have innocent civilians killed or injured,” Swanton added.

He said Monday that it was not clear how many people had been shot by police and how many by bikers.

Nearly 100 weapons — including brass knuckles, chains, clubs and firearms — were strewn across the site.

“It was a very gruesome, very violent crime scene,” Swanton said. “There were pools of blood, there were streams of blood … Probably one of the most violent, gruesome crime scenes I have seen in 35 years of service.”

He said at least 100 people were in custody for questioning late Sunday night and criticized the restaurant’s management for encouraging the biker gangs’ business.

“We have attempted to work with the local management of Twin Peaks to get that cut back, to no avail,” Swanton said. “They have been of no assistance. … Apparently, the management wanted them here.”

“We feel that there was more that could have been by the management,” he added. “Now we have nine individuals that are dead.”

The Dallas-based chain — which features scantily-clad waitresses and describes itself “the ultimate sports lodge known for its rugged man-cave atmosphere” — said it was “shocked” by the shootings that took place at its franchised restaurant in Waco.

“We are thankful no employees, guests or police were injured in this senseless violence outside the restaurant, and our sympathies are with the families of those killed,” it said in a statement.

Jay Patel, an operating partner for the Waco franchise, said his management team has had “ongoing and positive” communications with police and will continue to work with authorities as they investigate the incident.

Twin Peaks, in a statement, faulted the bar’s management and said it was immediately canceling the franchise agreement.

The management team “chose to ignore the warnings and advice from both the police and our company, and did not uphold the high security standards we have in place to ensure everyone is safe at our restaurants,” the chain said.

Swanton also admonished the restaurant for not heeding warnings from police. “We asked for assistance to keep this from happening, and we didn’t get that,” he said.

Swanton said police had been monitoring the restaurant for two months and there had been 22 officers, in uniform, monitoring the location before the violence broke out Sunday. “We were well seen. They could care less whether we were here or not,” he said.

McLennan County Sheriff Parnell McNamara, whose office is involved in the investigation, told The Associated Press that all nine who were killed were members of the Bandidos or Cossacks gangs.

In a 2014 gang threat assessment, the Texas Department of Public Safety classified the Bandidos as a “Tier 2” threat, the second highest. Other groups in that tier included the Bloods, Crips and Aryan Brotherhood of Texas.

The Bandidos, formed in the 1960s, are involved in trafficking cocaine, marijuana and methamphetamines, according to the U.S. Department of Justice.

The Texas assessment doesn’t mention the Cossacks.

There’s at least one documented instance of violence between the two groups. In November 2013, a 46-year-old from Abilene, who police say was the leader of a West Texas Bandidos chapter, was charged in the stabbings of two members of the Cossacks club.

NBC News’ Cassandra Vinograd, Erin McClam and The Associated Press contributed to this report.

This story originally appeared on NBC News