In a brazen scheme that may have involved escapes during prison visits, 20 inmates accused of being members of a major gang have slipped out of a Guatemalan prison and set off a sweeping manhunt, the authorities say.

The escapes took place over a period of time, but were only announced on Sunday, officials said. They came shortly after the American authorities designated the gang, Barrio 18, as a foreign terrorist organization, placing it on the same list as the region’s most notorious cartels.

The prison break has set off a nationwide manhunt, with 45,000 police officers taking part. It has also created a crisis for the government, with several prison officials dismissed and intense scrutiny falling on members of the president’s cabinet, though corruption has long plagued Guatemala.

Both members of President Bernardo Arévalo’s party and opposition lawmakers have called for an investigation.

The U.S. Embassy in Guatemala described the escapes as “utterly unacceptable,” and said in a statement on Sunday that the government “must act immediately and forcefully to recapture these terrorists, who pose a threat to both Guatemala and the security of U.S. territory.”

Guatemalan officials said they were coordinating with Interpol and the authorities in neighboring countries, “especially Mexico's,” to track down the fugitives, Interior Minister Francisco Jiménez said at a news conference on Monday.