PARMA, Ohio -- Surveillance video shows customers punching and shoving Chuck E. Cheese's employees during an attack Sunday night in Parma.

At least five patrons were involved in an attack on employees about 7:15 p.m. Sunday during a birthday party at the West Ridgewood Drive restaurant and entertainment center. The patrons involved in the fight fled before police arrived, and no one has been arrested at this time, police said.

The video, which is time-lapsed, shows a customer in orange throwing a punch. A customer wearing a blue hat then shoves a manager to the ground.

A second angle shows a scrum involving employees and customers heading out a kitchen door. Several women were then allowed back inside to retrieve their belongings, police said.

Two employees were seriously injured and treated at University Hospitals Parma Medical Center. Six employees were injured in total, including five who were treated at the hospital, Parma Police Lt. Kevin Riley said.

One of the injured employees is a teenage girl who was attempting to call 911. A customer hit her in the face and knocked her unconscious, Riley said.

"This is an attack on employees who were simply doing their jobs," Riley said.

The fight began after the customers, who were there celebrating a child's birthday, paid their bill. One of the customers complained about a photo booth that was not working, and a manager spoke to the group.

One of the customers was dissatisfied with the manager's explanation and followed him back to the kitchen area, where he attacked the manager. At least four other customers joined in, and at least five other employees attempted to break up the attack, police said.

"This was a vicious, unprovoked attack," Riley said. "From our investigation right now, it seems there was no reason for this incident to have occurred whatsoever."

Two employees described the attack in 911 recordings released earlier Monday.

"We're going to need cops, ambulances -- we're just freaking out," one of the 911 callers told a police dispatcher. "We're going to need people here."

Employees at Chuck E. Cheese's declined to comment and directed questions to the company's Irvine, Texas corporate office.

"We are anxious to bring these individuals to justice and are actively working with Parma police to provide information that will lead to their arrest," the company said in a statement released Monday. "We are deeply saddened that individuals would choose to behave in this manner in front of children and families."

Anyone with information is being asked to contact Parma police at 440-887-7300.