CEOAFRICA.com gathered from Brazil that at least 13 inmates lost their lives in a fight between two rival gangs in Pedrinhas prison Sao Luis, Maranhao.

Sources said riot police have been deployed to calm situation of things in the prison, as close to 30 people were reported injured.

Prison guards said fighting had broken out after they discovered inmates digging an escape tunnel.

Aluisio Mendes, Maranhao state security secretary said there was a tip-off that 60 inmates were digging a tunnel through which they were planning to escape at dawn.

"When the guards tried to access the cell in which the entrance to the tunnel was located, the prisoners tried to fight them off," he added.

It was gathered that immediately the tunnel was discovered, prisoners started a fire and members of rival gangs took advantage of the confusion to settle scores.

Relatives of inmates gathered outside the prison complex demanding information and threw stones at the guards.