WATCH: Brawl breaks out on cruise after passenger steps on flip flop

A Carnival cruise turned into a bloody brawl when someone reportedly stepped on another passenger's flip flop.

Dramatic video shows the chaos - up to 30 people fighting during a one-day South Pacific cruise on the 'Carnival Legend.'

Security guards stepped in, pinning some of the guests to the ground, and kicking two people. It was just one of several fights on board.

Some people with children reportedly locked themselves inside their cabins.

Carnival blames a large family for starting the fight. It says it cooperated fully with authorities in Australia to remove the family from the ship.

The company apologized to passengers, and it is offering them 25 percent off of their next trip.