NATAL, Brazil: The latest in a string of brutal prison massacres involving suspected gang members in Brazil is thought to have killed more than 30 people, including some who were beheaded, officials said Sunday.

The bloodbath erupted Saturday night in the overcrowded Alcacuz prison in the northeastern state of Rio Grande do Norte.

Similar violence at other jails in Brazil left about 100 inmates dead in early January.

“There are probably more than 30 dead” at Alcacuz, police investigator Otacilio de Medeiros told reporters after leaving the facility Sunday.

Security forces stormed the prison at dawn and restored order after 14 hours of violence, local authorities said.

Officials said members of two drug gangs clashed violently after coming out of different parts of the prison.

Officials in the southern state of Parana said 28 prisoners escaped from a jail in the city of Curitiba after inmates blew up a wall and fired on police.

At Alcacuz, security forces surrounded the prison but had to wait until first light Sunday to storm the site with armored vehicles, officials said.

Prisoners had cut off the electricity and were said to have firearms.

The prison, just outside the state capital Natal, was built for a maximum of 620 inmates but currently houses 1,083, the state justice department said.

Brazilian media said the riot was thought to be a clash between Brazil´s biggest drug gang, the First Capital Command (PCC), and a group allied to its main rival Red Command.

Experts say the violence is part of a war between drug gangs battling for control of one of the world´s most important cocaine markets and trafficking routes.