The mishap left 20 others injured.

According to the fire department, the bus carrying 40 passengers lost control and plunged into the ravine in the mountains area of Uniao dos Palmares municipality, reported Xinhua news agency.

The state government has announced three days of mourning.

The cause of the investigation is currently ongoing.

Brazilian President Luiz Inacio Lula da Silva promised assistance to the victims.

"My condolences to all the families of the victims involved in the accident. The federal government is monitoring the situation and will provide all necessary support to state authorities in providing assistance, care and support to the victims," the President wrote on X.

Brazil's racial equality minister Anielle Franco said she was deeply impacted by the tragic bus accident.

"Deeply impacted by the news of the tragic bus accident that occurred this afternoon on the way up Serra da Barriga, in União dos Palmares (AL)," the minister wrote on X.

"I would like to express my full solidarity with the victims and their families. We are monitoring the situation and trusting in the work of the rescue teams with the support of the União dos Palmares units and the support of the Government of the State of Alagoas," she said.