At least five inmates of at Ikoyi prisons are believed to have been killed in an electrical incident on Monday morning.
A member of staff told the BBC that the accident was caused by a power surge at the prison.
According to the source, after the surge, an electrical wire broke and fell on a bunk where inmates were sleeping.
Five inmates are believed to have been killed and a number of others are being treated in the hospital clinic.
The authorities are still investigating the incident.
Interior Minister Rauf Aregbesola visited Ikoyi prison following the accident