Nine police personnel and three journalists were injured as a grenade exploded at a press briefing this afternoon following the recovery of five grenades and arrest of four suspected JMB members in Gazipur.

Abdul Baten, superintendent of police (SP) of Gazipur, told The Daily Star that arrested JMB member Mamunur Rashid took the pin off a grenade at the press briefing at the SP office causing the explosion at about 5:00pm. Mamun was also injured.

The press briefing was meant to show journalists the grenades and ammunition seized from a house in Khartali area of Tongi in Gazipur.

Joydebpur police chief Abdur Rashid, sub-inspectors Omar Faruk, Mamun, Delwar, Detective Branch officer Abdul Hanif, constables Latif, Shajib, Gazipur correspondent of Channel i Fazlur Rahmanm, ntv's Nasiruddin and local journalist W Rahman were among the injured.

Six of them were admitted to Combined Military Hospital (CMH) in critical condition.

Police had earlier arrested Mamun and three women --Nurujjahan, Marjia, Mina-- suspected to be members of outlawed Jama'atul Mujahideen Bangladesh (JMB) and recovered five hand grenades from the house.

Acting on a tip-off, police raided a house in the area and recovered huge bomb making materials, some jihadi books and leaflets from the house.

Police chief Baten said the arrested people were believed to have been plotting attacks at the International Mother Language Day programmes.