LAUGHLIN, Nev. ÷ Thousands of bikers rumbled out of town yesterday as investigators sorted out the details of a casino brawl between rival motorcycle gangs that left three people dead.

Dozens of extra police patrolled the streets to guard against possible gang retaliation at one of the nationâs largest motorcycle festivals.

ãItâs just a mass exodus,ä said Sgt. Chuck Jones of the Las Vegas Police Department, which has jurisdiction over the casino town 80 miles southeast of Las Vegas. ãIf you go on the highway right now, itâs just motorcycle after motorcycle as far as you can see.ä

Gamblers ran for cover Saturday as 60 to 70 people fought inside Harrahâs hotel-casino. Police said gunfire erupted when an argument between the rival Mongols and Hellâs Angels gangs escalated.

ãBlow by blow, stab by stab, and shot by shot, we know exactly what happened in that casino,ä said Las Vegas police Lt. Vince Cannito after watching casino surveillance tapes.

ãIf there is any other event that precipitated what happened in there, we may never know.ä

All three of the dead were gang members involved in the fight, police said.

Calvin Schaffer, 33, a member of the Hellâs Angels, was arrested Saturday on suspicion of murder, Cannito said.

After interviewing more than 500 people, police said they arrested three to four people on outstanding warrants unconnected to the shooting, adding that more arrests are possible.

Police said they arrived at the casino two minutes after the casino erupted in gunfire. John Davidson, 39, ducked beneath a blackjack table during the melee.

ãThere were shell casings landing right by us,ä he said. ãI had to pull the dealer down. She was screaming.ä