CIUDAD JUAREZ, Mexico - Some prisoners learn woodworking or license-plate making. But bartending?

A prison workshop in northern Mexico where inmates were supposed to be learning trades was found to contain a bar behind bars _ complete with beer, vodka, tequila, and billiard tables.

Federal police and local authorities discovered the bar Monday at a minimum-security prison in the northern state of Chihuahua, the state attorney general's office said in a statement.

Seized from the site were 20 bottles of vodka, 12 bottles of tequila, and 200 beer cans. Police also found three guns, 20 cell phones, 180 individual doses of marijuana and 90 doses of heroin.

The prison's deputy director was fired Wednesday and prison guards are under investigation, said Jorge Chaires, a spokesman for the state's prosecutor for prisons.

Also Wednesday, guards conducting a routine check at a prison in the northern state of Tamaulipas discovered 17 inmates missing, the state's Public Safety Department said in a statement. The prison is located in Reynosa, across the border from McAllen, Texas.

Authorities later found a tunnel leading out of the prison from the laundry room, the statement said. The prison's director and eight guards were being questioned.

Security at Mexican state prisons is notoriously lax. Jailbreaks are common, inmates are often found to be directing criminal operations from behind bars, and corrupt guards are often found to be involved.