The biker brawl that left nine dead in Texas is one of the bloodiest shootouts in motorcycle gang history.

Terrified families watched in horror as rival gangs attacked each other with clubs, knives and chains outside the Twin Peaks Sports Bar and Grill, an infamous biker watering hole in Waco.

Officials have not named the chapters involved, but Waco Police Sergeant Patrick Swanton said up to five gangs were involved. He declined to give names.

Photographs of the dozens arrested show many in leather jackets bearing the names of three motorcycle gangs: Bandidos, Cossacks and Scimitars.

Sgt Swanton described the bikers as dangerous - and added: "This is not a bunch of doctors and dentists and lawyers riding Harleys. These are criminals on Harley-Davidsons."

He said the fight "started over a parking issue" - but another law enforcement official said the rivals need no incitement, and simply crossing paths is enough to spark violence.

The rivalry between US biker gangs began in 1969 when a member of the Outlaws raped the wife of a Hells Angel.

In revenge, Hells Angels members almost beat the rapist to death in New York.

Outlaws kidnapped three Hells Angels and shot them at pointblank range. Their bodies were thrown in a Florida quarry.

Since then there has been tit-for-tat biker gang violence all over the world.

So what do we know about the Bandidos, Cossacks and Scimitars involved in the Twin Peaks bloodbath?

• Bandidos

They are the largest of the three named gangs, and have an estimated 2,400 members in 22 countries around the world.

The FBI has classified them as an organised crime syndicate, engaged in murder, drug trafficking, money laundering, extortion and gun running.

The club was formed by Vietnam War veteran Donald Chambers in San Leon, Texas, in 1966, and their motto is "we are the people our parents warned us about".

Their patch is a man in a sombrero holding a sword and a gun. They have a saying: "Cut one, we all bleed."

According to the Texas Department of Public Safety, they are the most dangerous biker gang in the state.

Officials have classified them as a "Tier 2 threat" - the second-highest level - "responsible for a disproportionate amount of crime across urban, suburban and rural areas of Texas".

Worldwide, the Bandidos were involved in the "Great Nordic Biker War" with Hells Angels in Scandinavia from 1994 to 1997.

Gun fights, bombs and even an anti-tank missile fired at a prison cell holding a Bandidos member resulted in an estimated 11 murders and 74 attempted murders.

They were also involved in the largest mass killing in the history of Ontario, Canada, when they carried out an "internal cleansing" in 2006. Eight members were found shot dead in cars.

Duncan McNab, who has written three books on biker gang culture, told Sky News: "The Bandidos are probably the second largest gang in North America.

"They've been around a long time and they've spread into Europe and Australia and more recently South East Asia. They are a very powerful, very aggressive group who protect their turf hard."

• Cossacks

The rivalry between the Cossacks and Bandidos goes back to at least 2013 when Bandidos leader Curtis Jack Lewis allegedly stabbed two Cossacks outside a restaurant in Texas.

Photographs of Cossacks arrested in Waco show mainly white gang members sporting neo-Nazi tattoos and symbols.

They were founded in Texas in 1969, according to the book The One Percenter Encyclopedia: The World of Outlaw Motorcycle Clubs.

Their colours are gold and black, and their patch is a cossack warrior brandishing a sword.

Their motto is "we take care of our own".

Although relatively small in the US, they are one of the major motorcycle groups in Australia.

• Scimitars

The Scimitars are the least well known of the gangs involved in the shootout.

They are aligned with the Cossacks, and have previously supported them in their feud with the Bandidos.

The gang was formed in Texas and their patch is a red-eyed skull on two crossed scimitars.