Buenos Aires, Argentina ? A fire set by feuding inmates raged through a cellblock at a prison southeast of Buenos Aires early Sunday, killing 32 inmates and leaving two jailers injured, authorities said.

All the deaths appeared to have been caused by asphyxiation after inmates were overcome by smoke, said Justice Minister Eduardo Di Rocco of Buenos Aires province, where the prison is located.

Di Rocco said inmates first began fighting just before midnight and then set mattresses and blankets alight. The fire spread through one of several cellblocks in the sprawling prison.

Di Rocco added that it was unclear what caused the disturbance but he rejected initial reports that a demand for more visiting hours for relatives led up to the blaze.

He said the warden rushed to the scene and was critically injured by a blow to the head and had to be hospitalized along with a second jailer.

Di Rocco had no information on survivors other than to say 16 others in the unit would be interrogated to determine the exact chain of events.

Earlier Sunday, some 500 relatives anxiously massed outside the prison, demanding to know about their loved ones. The fire occurred on the date Argentines traditionally celebrate Mothers’ Day, and many women had gone to the prison to see imprisoned relatives.