US police have found more than 1000 weapons hidden in a restaurant in Waco, Texas, where nine people died in a bikie gang shootout.

The weapons, which were tucked away in the kitchen area, toilets and under benches of the Twin Peaks restaurant.

They were left behind after a bloody melee that erupted among five rival bikie gangs on Saturday, the Waco Tribune-Herald reports.

"It goes to show the criminal intent," Sergeant Patrick Swanton said.

"(It) indicates to the public that these are not clubs, these are criminal gangs that came here with the intent or anticipation of violence."

The weapons included pocket knives, assault knives, batons, an AK-47 rifle and body armour.

The arms were left behind among half-eaten hamburgers, half-drunk margaritas and beer bottles covered with gang symbols.

Five rival bikie gangs gathered at the restaurant, and the fighting started with guns, knives and beatings inside before moving into the parking lot of the restaurant.

Police arrested 170 people after the incident, which left 18 people injured.

All 170 arrested gang members are being charged with "engaging in organised crime in reference to the shootings at Twin Peaks which is a capital murder, because of the number of people killed here," Swanton said in a press conference earlier this week.