A state court judge declared a mistrial Wednesday in a felony attempted murder and gang activity case against eight Hells Angels stemming from a December 2008 brawl with rival Mongols motorcycle club members at a downtown Las Vegas wedding chapel.

Clark County District Court Judge Michael Villani ruled Wednesday that prosecutors failed to fully turn over to defense attorneys evidence including photographs and documents to be used during the trial, court officials and defense lawyers Tom Piraro and Chris Rasmussen said.

Prosecutors Chris Owens and Sonia Jimenez weren't immediately available for comment. An aide to Clark County District Attorney Steve Wolfson said a decision wasn't immediately made on whether to seek a retrial.

The judge's ruling was first reported by the Las Vegas Review-Journal. It came on what would have been the seventh day of testimony in the trial of eight of 13 men who pleaded not guilty after their July 2010 indictment. Jury selection began July 16.

Five other alleged assailants are due to stand trial in coming weeks. Villani is scheduled to meet with prosecutors and defense attorneys Aug. 7, ahead of one scheduled trial Aug. 13.

Each of the 13 defendants is accused of attempted murder, battery, assault, conspiracy and taking part in activities of a criminal gang. Each has pleaded not guilty.

Defense attorneys say their clients were at A Special Memory Wedding Chapel to attend a wedding, and acted in self-defense when they unexpectedly encountered Mongols arriving for another wedding. Six people were hurt, including two who were stabbed.

No one was arrested immediately after the brawl. Police spent months developing the case before serving search warrants in November 2009 at six sites in and around Las Vegas and Henderson.

Hells Angels and Mongols have feuded for years, and tensions were high before the wedding chapel confrontation.

Three months earlier, in September 2008, a Mongols member in California killed the president of the Hells Angels' San Francisco chapter outside a Bay Area bar. The assailant in that case is now serving life without parole in federal prison.

The two outlaw motorcycle clubs also clashed at a 2002 motorcycle rally in Laughlin, a resort town about 100 miles southeast of Las Vegas. Two Hells Angels and one Mongol member died in a gunbattle inside a casino, and more than 12 people were injured.