Standoff at Brazil prison where 26 killed over weekend

Inmates gesture and talk on cell phones as they stand on the roof of a building amid tension between rival gangs in the Alcacuz prison in Nisia Floresta, near Natal, Brazil, Friday, Jan. 20, 2017. (AP Photo/Felipe Dana) (The Associated Press)

An inmate walks on the roof of a building amid tension as confrontation between rival gangs continue in the Alcacuz prison in Nizea Floresta, near Natal, Brazil, Friday, Jan. 20, 2017. (AP Photo/Felipe Dana) (The Associated Press)

Inmates walk amid tension as confrontation between rival gangs continue in the Alcacuz prison in Nizea Floresta, near Natal, Brazil, Friday, Jan. 20, 2017. (AP Photo/Felipe Dana) (The Associated Press)

Inmates armed with knives and cell phones are holding their ground at a prison in northeast Brazil where 26 were killed.

Tensions at the Alcacuz prison outside of Natal remain high Friday, a day after inmates from rival gangs fought in the yard and set up barriers of doors and mattresses.

Authorities have yet to regain control of the prison, and there's fear that more violence will spill over to the city, where already 20 buses have been burned.

The governor has asked for troops to be dispatched to help maintain control.

On Thursday evening, a riot squad briefly entered the prison to remove several inmates who had been injured during clashes. However, they did not send inmates back to their cells or break up the two sides.