Police say some kids, along with several adult victims, were struck.
Officers later arrested four suspects in connection with the brutal brawl.
"There was some disturbance inside in relation to someone in the bathroom when that person came out they attacked one of the victims, then the family members jumped in and started attacking members in the original party," said Sgt. Gary Williams.
The call came in a little after 6 p.m. to the Las Playas restaurant on Chinowth Street and Noble Avenue.
Investigators say a patron told them she walked into the bathroom, and two people were having sex in a stall.
They say she asked them to stop so she could use the bathroom, but moments later, the fight started.
"When the two individuals in the bathroom came out, they asked who walked in. that person identified themselves, and they were assaulted," Sgt. Williams said. "There was a grandmother holding a one-year-old child when she was assaulted."
Three of the suspects were arrested in the parking lot.
Ricardo Garza tried to escape in a car but crashed it less than half a mile away at Meadow Avenue and Chinowith street.
The owner of Las Playas, says they've never had anything like this happen, and will make sure it doesn't happen again.
Jesus Villegas says they plan to be more careful and to be more aware of what's happening while keeping an eye on those drinking.
The four suspects are facing several charges, including assault with a deadly weapon, and child endangerment.
The owner says those four arrested will not be allowed back.
At least three victims were taken to Kaweah Delta Hospital to be evaluated for their injuries.