Nine inmates were electrocuted Wednesday while trying to escape from one of Cameroon’s largest prisons, a staff member of the justice minister said.

Their bodies were found draped around the prison’s perimeter fence, the staffer said. The electrocution set off a fire that seriously burned around 20 other prisoners trapped in their cells. They had second-degree burns, the staff member said.

Cameroon’s justice minister was heading to the prison in the commercial capital, Douala, and was expected to make a formal announcement. The staff member spoke on condition of anonymity because he was not authorized to speak to the media.

Jail breaks are common in West Africa’s crumbling and overcrowded prisons, where inmates are often not given enough to eat. In June, guards shot dead 16 prisoners who tried to escape from the same facility.

The decrepit prison was built in the 1930s to hold about 800 inmates _ but has at least twice that number.