Nashville police are investigating a privately operated juvenile detention center where four teens, including two accused of murder, were able to escape through the front door, police said Monday.

Youth Opportunity Investments, the private detention contractor that manages the Davidson County Juvenile Detention Center, waited more than a half hour before it told police that the teens escaped, according to the Metro Nashville Police Department, which is investigating the circumstances surrounding Saturday night’s escape.

“In 30 minutes, with a fast walk, you could be 2 miles away,” Metro Nashville Police Department Chief Steve Anderson told reporters Monday. “I don’t have any indication that a crime has been committed, that there was some overt act to assist in their escape, but certainly a lot of gross negligence.”

Murder suspects Decorrius Wright, 16, and Morris Marsh, 17, allegedly ran out of the Davidson County Juvenile Detention Center at around 10 p.m. Saturday night along with two other inmates, identified as 17-year-old Brandon Caruthers and 15-year-old Calvin Howse, authorities said Sunday.

The teens were on a work detail when their staff supervisor left them to address a fight at another location inside the facility, according to police. They managed to get onto an elevator and used staff protocols to ride to the unsecured ground floor where they went through a series of doors and exited to the outside.

Authorities said an employee of the detention center drove around the area looking for the escapees for 35 minutes before he eventually called police for assistance.

The teens had not been apprehended as of late Monday night. Investigators said they more than likely had assistance once they were outside.

Youth Opportunity said it was conducting an internal investigation into how the teens managed to escape. It said four employees had been placed on suspension pending the results of the internal probe, according to Nashville ABC affiliate WKRN.

“Youth Opportunity has provided a safe and secure environment for the youth and the citizens of Nashville. Youth Opportunity has heretofore experienced very few safety and security breaches,” the company said in a statement. “Youth Opportunity acknowledges that several members of its security personnel made improper decisions that, when combined, led to an opportunity for the four youth to leave the facility.”

Anderson said he “had more questions than I had answers” after reviewing a copy of Youth Opportunity’s internal report, which is why he requested an investigation.

“In looking at their own internal report, I just saw a pattern of people not paying attention to what they should be doing, so that’s the reason that I called for the review,” Anderson said.

“What I saw in their report appeared to be a pattern of maybe nonchalant behavior,” Anderson said.

Authorities said the teens are considered dangerous and are asking for the public’s help in locating them.

Wright is accused of the murder of 24-year-old Kyle Yorlets, a Nashville musician who was fatally shot in an alley behind his home in February, according to police. Marsh is suspected of killing 19-year-old Charles Easley in April.

Caruthers had been transferred to adult court on an August 2018 armed robbery case in south Nashville, according to police. Howse was last arrested Nov. 21 on charges of auto theft and gun possession, police said.

ABC News does not normally name juveniles, but are doing so because police said they are dangerous individuals and have released their names and photos. Anyone with information about the escapees is asked to immediately call Nashville’s Emergency Communications Center at 615-862-8600.