DENVER (AP) — Two men escaped from a Denver area immigration detention center apparently after its back doors opened during a power outage, police said.

Despite claims by immigration officials, police in Aurora said they weren’t notified until early Wednesday, about two hours after the men were discovered missing from the facility, which they said was too late to help.

In a statement sent to The Associated Press Thursday, U.S. Immigration and Customs Enforcement said the men, who had previously been held in Colorado jails on unspecified charges, were still at large and a search was ongoing. It also said law enforcement authorities were notified immediately about the escape but declined to help in the search.

Federal officials and Republican lawmakers have criticized what are often known as sanctuary policies in places including Denver that limit cooperation with federal immigration enforcement. Colorado also has state laws that restrict cooperation. However, Aurora police said they have an agreement with the GEO Group, the private company that runs the detention center, to help with escapes but only when they are notified within 15 minutes of an escape.

A facility staffer called 911 to report a possible escape at around 2:30 a.m. Wednesday but didn’t provide enough details, prompting a police commander to call back to get more information, Aurora police said in a timeline based on its records and information obtained from GEO Group. Since it was later determined the escape was believed to have happened around 10 p.m. Tuesday, an officer did not go to the facility to follow up until around 5 a.m. Wednesday, according to the timeline.

An assistant administrator told the officer they realized the men — one from Mexico and one from Venezuela — were missing during an emergency headcount conducted because of the power outage, the officer’s report said. Staff believe they escaped through doors leading to a soccer field, it said.

“In order for us to effectively respond to and assist our federal partners with calls for service, we need to receive timely and accurate information. That unfortunately did not happen, as demonstrated by the facts of this incident,” Aurora Police Chief Todd Chamberlain said in statement.

Chamberlain has expressed a willingness to work with ICE, which helped in the department’s investigation into a violent December kidnapping and assault believed to involve members of the Venezuelan gang Tren de Aragua.

The state, meanwhile, issued a notice to law enforcement agencies to “be on the lookout” for the men but ICE did not ask for any other help, a spokesperson for Democratic Gov. Jared Polis, Ally Sullivan, said in a statement.

“We continue to urge ICE to be transparent with the state and the public about this incident as it develops, including whether any escapees are a danger to the public,” Sullivan said.

A spokesperson for ICE did not immediately respond to a request for details about the search or to comment on the police account of what happened.

The Florida-based GEO Group did not respond to an email request seeking comment about the escape.