Mexico City - Some 21 inmates died and at least 10 others were wounded in a clash between prisoners in a federal penitentiary in the northern Mexican city of Reynosa, according to preliminary information made public by authorities.

Tamaulipas state Interior Minister Jose Soberon said that the riot occurred early Monday.

Jail authorities said that the uprising was "in the process of being brought under control."

"There was a clash between inmates. A group of inmates attacked others, and 21 people lost their lives, besides 10 or 11 injured," a state Interior Ministry official told Deutsche Presse-Agentur dpa by telephone.

The riot, including a fire, happened around 3 am in the prison, which has a population of 1,600 inmates. Police and the Mexican Army were at the scene.

Reynosa, a city with a strong presence of drug cartels, is just across the US border from McAllen, Texas.

Two of the wounded prisoners were apparently in serious condition.

Unofficial reports said some of the dead succumbed during the blaze that started during the riot, while others were killed by gunshots.

On October 9, 17 inmates including five reputed assassins for a drug cartel, escaped from the penitentiary through the main gates, allegedly aided by four prison guards. dpa