A Walmart in Rialto, Calif., decided to open an hour early on Black Thursday when they realized 3,000 people had already lined up outside.
The early opening led to a melee in which a police officer was sent to the hospital.
Two fights occurred around 7 p.m., when the store opened its doors, over items inside the store.
A third fight between three people occurred in the parking lot. A police officer sustained a broken wrist while trying to break up the fight. Two of the men involved were arrested for suspicion of assault with a deadly weapon.
"There were some tensions that flared up in reference to people cutting in lines," Sergeant Nicholas Borchard of the Rialto Police Department told CBS LA.
All of those involved in fights were taken into custody.
Rialto police officers were assisted by Colton Police and the San Bernardino County Sheriff’s helicopter.
“The fight at the Rialto store was an unfortunate and isolated incident to an otherwise very safe event,” said Walmart spokeswoman Betsy Harden. “Providing our customers with the best and safest shopping experience is always our top priority.”