DENVER (KDVR) — Police are looking into an alleged “incarceration room” at a Denver middle school, FOX31 has learned.

Members of the Denver Public Schools board said Thursday that a staff whistleblower exposed the room at McAuliffe International School. The room had locks on doors and windows to prevent anyone inside from leaving.

Police told FOX31 on Friday that they received a complaint, and an investigation is underway.

The whistleblower shared photos of the room, which were distributed by members of the Board of Education. One of the photos shows what is described as a barrel bolt latch on the outside of room 121E. Another shows a padlock on a window.

“Students of color were locked in this room multiple times last year,” the anonymous whistleblower stated in an email, according to Board of Education Vice President Auon’tai Anderson.

In a statement Friday, the school district said it’s aware of at least three students who were placed in the room at McAuliffe during the last school year.

‘Seclusion rooms’ prohibited in Denver schools

Denver Public Schools prohibits rooms like this, which it formally refers to as “seclusion rooms” in its written policies. The term “de-escalation room” was also used during a Thursday news conference with board members, which the district describes as an open-door quiet room to help a student regulate emotions, but only with the company of an adult.

“We have learned that what is said to have allegedly occurred at MIS was not de-escalation but seclusion. Seclusion is when a student that is experiencing escalating emotions is locked into a room by themselves until they calm down. De-escalation is allowed in DPS in certain circumstances. Seclusion is not,” the statement reads.

The district said the room “was clearly not in compliance with DPS’ stated guidelines.”

The allegation has board members concerned about what they say is possible oppression and systemic racism at McAuliffe.

“The fact that the room was called an ‘incarceration room’ by a staff member at the school in a work order to have it removed says enough,” Anderson said.

The allegations were made while DPS school board members were planning to vote on whether to uphold the termination of Kurt Dennis, the school’s principal.

An attorney for Dennis said the principal was not disciplined for these allegations, and he said these types of rooms are standard in schools to calm down violent students.

“Instead of calling the police, the teacher alerts the principal, Kurt in this case, who then goes with an administrator who goes to the classroom, and they gain control of the violent student and walk that student to the de-escalation room,” Lane told FOX31 on Thursday. “The theory is the kid calms down for 15 minutes and a psychologist goes in and talks to the kid, and they try to work through and de-escalate the problem.”

Dennis said he believes he was fired after giving an interview criticizing the DPS policy to have administrators pat down students who need extra security screenings. Those statements came after a shooting at East High School.