MEXICO CITY (AP) — A group of 29 inmates have tunneled their way out of a prison in the northern Mexico border state of Tamaulipas, authorities said Thursday.

One of the inmates shot to death a passing motorist in an apparent carjacking as part of the mass escape in the state capital, Ciudad Victoria.

The Tamaulipas state security spokesman Luis Alberto Rodriguez said 12 of the 29 have been recaptured.

Rodriguez said the inmates had dug a tunnel about 5 yards (meters) deep and 40 yards (meters) long to flee.

Rodriguez said the tunnel was hidden in a hut that inmates had illegally constructed in a part of the prison they essentially controlled.

Overcrowding, corruption and inmate control of prison areas have been persistent problems in Mexican prisons.

Rodriguez said about 30 guards at the facility had been placed under investigation, and appealed for help from neighboring states in re-apprehending the escaped inmates.

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He said the prison dates to the 1940s and was outmoded. State authorities have been looking into moving the prison to other facilities, outside the city.

Ciudad Victoria has been dominated for years by the fragmented Zetas cartel.