CALDWELL -- A search is underway for two inmates who escaped from the Canyon County Jail Saturday night.

According to the Canyon County Sheriff's Office, Jeffrey Duvall and Juan Cervantes escaped from the jail's tent structure at about 10:30 p.m.

The men were last seen on foot heading eastbound on Chicago Street in Caldwell, officials said.

Duvall and Cervantes were both being held on felony probation violations. Duvall is also charged with attempted strangulation and domestic battery with traumatic injury, while Cervantes was in custody on charges of DUI, driving without privileges and possession of a controlled substance.

The sheriff's office said in a news release that area law enforcement are actively looking for the pair, and ask for anyone with information on their whereabouts to call police.

Deputies say the circumstances surrounding the escape are under investigation.

Saturday's escape marks the fourth time inmates have escaped from the jail in less than a year. In December, Jesus Cuevas climbed a security fence during outdoor recreation time. In January, Jose Coronado used a jail-issued razor to cut his way out of the tent. And in August, like Cuevas, Abel Garcia climbed a fence to escape.

All three of the previous escapees were eventually captured.

The tent structure was build to ease overcrowding at the jail, and it was never intended to hold inmates for extended periods of time.

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After the escape in August, Canyon County Sheriff Kieran Donahue expressed his frustration at the escapes, calling them "simply ridiculous," and saying that it is time the county looks for long-term solutions to address the jail issues "once and for all."