The latest in a string of brutal prison massacres involving suspected gang members in Brazil has killed 26 inmates, most of whom 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 around 100 inmates dead in early January.

"Twenty-six deaths have been verified," the state's public safety manager, Caio Bezerra, told a news conference. The authorities had earlier estimated around 30 were killed as they gathered bodies and body parts, he said.

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

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

One family member said the authorities did not seem to be doing everything they could -- even after she warned the prison director.

"The (prison) director even said he could not do anything" when told an uprising was looming, said Adriana Feliz, the sister of an inmate.

President Michel Temer said on Twitter that the federal government stood ready to provide "all assistance necessary."

Separately, 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.

Violence in the first week of January left around 100 prisoners dead -- many of them active gang members, the authorities said.