An eight-year-old girl survived and was airlifted to hospital in serious condition.

A bus has plunged off a bridge into a ravine in South Africa, killing 45 of the 46 passengers on board, according to the Department of Transport.

The only survivor, an eight-year-old girl, was airlifted to hospital with serious injuries after the crash on Thursday.

Authorities said the driver lost control of the vehicle and crashed through the barriers on a bridge in a mountainous area near Mamatlakala, 300 kilometres (190 miles) north of Johannesburg. The bus plunged 50 metres (164 feet) into a ravine before bursting into flames.

The bus was on its way from neighbouring Botswana to Moria, a town in northern Limpopo province that holds a popular Easter festival. Easter Sunday falls on March 31 this year.

Transport Minister Sindisiwe Chikunga travelled to the scene of the crash and promised a full inquiry.

“We want really to extend our heartfelt condolences to the families but also to the government of Botswana and to the people of Botswana, and as South Africa, we will try everything to assist so that they go back to their country and families to be buried with dignity,” she was quoted as saying by national broadcaster SABC.

South African President Cyril Ramaphosa sent his condolences to Botswana and promised support, his office said in a statement.

Search operations were continuing at the site, but many bodies were burned beyond recognition and were still trapped inside the vehicle.

While South Africa has one of the African continent’s most developed road networks, it also has one of the worst safety records.

A few hours before the crash, Ramaphosa had appealed to South Africans to take care when travelling during the Easter holidays.

“Let’s do our best to make this a safe Easter. Easter does not have to be a time where we sit back and wait to see statistics on tragedy or injuries on our roads,” he had said in a statement.