The Civilian Office of Police Accountability on Friday broadly detailed an investigation into “a sexual misconduct allegation” involving officers from the Ogden police district and at least one immigrant who was temporarily housed there.

COPA said the oversight agency learned of the alleged misconduct on Thursday and notified the police department’s Bureau of Internal Affairs, which formally opened an investigation.

A police spokesperson initially issued a statement Thursday night saying an investigation into claims of sexual impropriety had jointly been opened.

An officer assigned to the Ogden District, covering Lawndale and Little Village, has been accused of impregnating a teenage girl, law enforcement sources have said. Multiple other officers were also accused of engaging in sexual acts with immigrants.

The details and scope of the investigation remain unclear, though COPA has said the allegations haven’t been corroborated. Still, the agency noted that investigations involving alleged sexual misconduct “may involve criminal actions and require cooperation with CPD and ultimately, the Cook County state’s attorney’s office.”

“While COPA investigators are currently determining whether the facts and details of this allegation are substantiated, we want to assure the public that all the allegations of this nature are of the highest priority and COPA will move swiftly to address any misconduct by those involved,” COPA First Deputy Chief Administrator Ephraim Eaddy said in the agency’s statement.

“In compliance with the consent decree,” he added, “COPA has jurisdiction to conduct the administrative investigations of sexual misconduct allegations involving Chicago Police officers and we are obligated to demonstrate our commitment to objectivity, integrity and transparency when responding to misconduct.”

As the city has struggled to accommodate an influx of new arrivals being sent from the southern U.S. border, controversy has brewed over the decision to temporarily house many of them at police stations.

About 11,000 asylum seekers have come to Chicago since last August. Many were placed on buses or planes and driven to the city at the direction of Texas Gov. Greg Abbott. Chicago has grappled with finding adequate shelter for the new arrivals.

Hundreds have had to spend nights sleeping on the floors of police stations. To ease the burden on the stations, the city has turned to housing immigrants at temporary locations like Wilbur Wright College on the Northwest Side.

Most of the asylum-seekers reaching Chicago are from Venezuela. Others are from Colombia, Ecuador, Nicaragua, Peru, Honduras, Mexico, El Salvador, Russia, Cuba, Angola and the Dominican Republic.