Police said the blast occurred during an inspection at the headquarters’ warehouse at 11:15am.

The victims were shifted to a hospital, police said, adding that the two deceased and an injured were constables while the other injured was a sub-inspector of police.

Police said that investigations of the incident are underway.

Deputy Inspector General (DIG) South Sharjeel Kharal told the media that the inspections were being carried out at police warehouses in the wake of recent rains. “It is a routine practice to defuse explosive material,” he added.

He said the hand grenade was being defused when it exploded and that the teams of the bomb disposal squad and the counter-terrorism department (CTD) were investigating the incident, he added.