MANILA (3rd UPDATE) - A grenade exploded in the New Bilibid Prisons (NBP) in Muntinlupa City early Friday morning.
Southern Police District (SPD) Director Benito Estipona said the incident occurred in Building No. 11 inside the compound of NBP at around 6:15 a.m.
The explosion, however, was reported only to police authorities at around 10:30 a.m.
Muntinlupa City police chief Senior Supt. Conrad Capa said a closed-circuit television (CCTV) camera footage showed that prisoners were jogging inside the maximum security compound of NBP when one inmate suddenly hurled a fragmentation grenade.
At least six people were reportedly injured from the incident.
Police said the victims only sustained minor injuries. They are currently seeking treatment in the NBP Hospital.
NBP Supt. Ramon Reyes said the suspect behind the blast has already been arrested. Police refused, however, to identify the suspect.
Reyes said the six victims are members of the Batang City Jail.
He said it is possible that gang war is the motive behind the explosion.
Authorities also said that the explosion was planned.
Authorities are still conducting investigations into how an inmate managed to get hold of an explosive device inside the NBP.
Meanwhile, NBP said visits to the prison compound will be temporarily suspended until Saturday. -- Report from Dexter Ganibe, dzMM