A youth psychiatric center where a brawl broke out last month is at risk of losing its license as Utah state officials investigate claims of sexual abuse, violence and several other issues.

Investigators say the Red Rock Canyon School in St. George must make more than a dozen significant changes to keep its license, according to a letter posted to Utah's legislative website Friday.

State officials outline nine violations in the letter, including the school's failure to report the brawl until days later. Staffing problems at the school have left residents and staffers feeling unsafe, culminating in the fight that broke out April 28, according to the letter from the Department of Human Services.

A voicemail left at the school was not immediately returned.

A brawl that sent five people to the hospital and injured a total of 20 people started at about 8 p.m. and led to the closure of an entire city block in front of the school as curious bystanders watched as armed officers rushed in.

It took police officers about an hour to get it under control at the school 300 miles (480 kilometers) southwest of Salt Lake City. The school serves about 100 teenage boys and girls suffering from mental health-related issues, including about two dozen from Oregon's child welfare system.

Officials claim the staff escalated the brawl by making "humiliating and degrading comments" to residents.

Five youths face a felony-level charge of rioting, Washington County prosecutor Angela Adams said.

Changes ordered by the state include reducing the number of residents to 60 to meet supervision requirements and training staff in de-escalation skills and behavior management.

Red Rock Canyon School has been the focus of a number of lawsuits in recent years, many concerning staffers who have allegedly physically or sexually abused residents.

Two lawsuits filed last year accuse the school of overlooking the sexual abuse of two youths by former employee who is now a registered sex offender. The school defended its actions in court filings, saying it had no reason to believe the employee was a danger to students when he worked at the school.