(UPDATE) 1 killed in NBP blast

MANILA, Philippines (Xinhua) - At least one was killed and 19 others were injured in an explosion inside the New Bilibid Prison (NBP) this morning, the Bureau of Corrections said.

The incident took place at around 9:45 a.m. local time when an alleged hand grenade exploded inside the security compound of the national penitentiary located in Muntilupa City, Metro Manila.

The fatality died in the hospital inside the NBP while being treated.

Investigation has been ongoing into the incident.

Officers of NBP have been under fire after authorities conducted raids last month following reports that convicted drug lords still managed to continue with their illegal drug trade even under custody.