Surveillance video of a shootout between rival motorcycle gangs at a Texas restaurant in which nine people were killed, has been leaked.

The footage - apparently part of the evidence that has been gathered against 170 bikers arrested after the shoot-out - shows members of the Cossacks gang eating and drinking with bikers from rival groups at the Twin Peaks restaurant in Waco on 17 May.

A fistfight that broke out quickly escalated to include knives and firearms, and gang members then spilled into the car park. There, they began firing at each other.

Nine suspected gang members were killed and 18 people were hospitalised, mostly for gunshot and stab wounds, police said.

In one video, the gunfire erupts just off camera. Some bikers can be seen grabbing guns while others throw themselves to the floor and crawl to safety. One surveillance camera catches a biker firing a shot toward the parking lot as he runs inside the restaurant.

The videos also show terrified Twin Peaks restaurant workers running for cover. Minutes later, the video shows a parade of bikers surrendering with their hands up.

Officers were already at the scene when the shooting started, authorities said at the time, and responded within 30 to 45 seconds. Some officers returned fire at the bikers. No officers were injured, police said.

Police said that once the restaurant was cleared, they found hundreds of weapons -- from guns to batons and knives -- hidden in sacks of flour, bags of tortilla chips and tucked beneath benches.

The videos, which were first obtained by CNN,were leaked as a grand jury in Waco is currently hearing all the cases against the bikers.

Police and prosecutors said they worried that the video leak could affect the outcome.

John Wilson, president of the Waco-area chapter of the Cossacks, told CNN: “I couldn't even see who threw the punch. But I saw our guy's head go back, and it looked like he was getting ready to punch back whoever did it and a shot went off.”

Sergeant Patrick Swanton, of Waco Police, said the footage and documents had not been authorised for release.