TUCSON, Ariz. An Arizona prison has been locked down after three guards were injured today while trying to break up a dining room brawl.

The fight broke out among several inmates at a detention facility in Tucson. Officials say about 30 inmates barricaded themselves in the dining hall afterward.

A prison system spokesman says the prisoners initially refused to surrender, but gave up after a chemical similar to tear gas was dispersed.

The melee occurred on the eve of the first anniversary of last year's hostage standoff at Arizona State Prison Complex-Lewis. Two guards were taken hostage for 15 days in a tower.

Negotiators finally talked the inmates into surrendering.

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