The incident occurred at a facility in the southwestern city of Tuluá.
Dozens of prisoners have been killed and injured during an attempted escape from a facility in Colombia, officials have said.
A spokesman for the country's prison administration (INPEC) told AFP that at least 49 prisoners had died in a fire after the escape attempt.
According to local media, a prison riot broke out as several inmates set fire to their mattresses in the medium-security prison.
The number of casualties from the incident in Tuluá, southwestern Colombia, is expected to rise.
Outgoing Colombian President Iván Duque confirmed the tragedy on Twitter, without giving further details.
"We regret the events that occurred in the prison of Tuluá, Valle del Cauca," he wrote on Tuesday.
"I am in contact with the director of INPEC and I have given instructions to carry out investigations to clarify this terrible situation. My solidarity with the families of the victims."
The Tuluá prison -- located 92 kilometres from the regional capital, Cali -- houses around 1,200 inmates.