FOUR inmates inside the New Bilibid Prison (NBP) were wounded in a clash between members of the Bahala Na Gang and Sputnik Gang.
NBP Superintendent Richard Schwarskopf said the incident happened around 2 p.m.
He said they are still investigating the cause of the incident.
The wounded inmates were brought to the NBP Hospital while the other inmates involved in the clash were locked up at the disciplinary cell.
Schwarskopf said they also conducted an immediate inspection of the area where an improvised deadly weapon was confiscated.
The tension occurred a day before former East Mindanao Command chief Ricardo Rainier Cruz III takes his oath as new chief of the Bureau of Corrections (BuCor) replacing retired police general Franklin Jesus Bucayu.