Authorities say a carjacker has escaped from a federal prison in California’s San Joaquin Valley.

Guaymar Cabrera-Hernandez, 26, was discovered missing Friday night from the Atwater penitentiary. He remains at large Saturday.

Merced County Sheriff Vern Warnke told the Merced Sun-Star that local authorities weren’t notified of the escape for at least four hours.

Cabrera-Hernandez was housed in a maximum security area, and authorities haven’t confirmed how he escaped.