Three assailants on a motorcycle have gunned down a prison guard of Kashimpur jail in Gazipur in broad daylight and fled away, police say.

Rustom Ali, 60, a sergeant instructor of Kashimpur jail, was shot when he was sitting in front of a shop near the prison around 11:15am, our Gazipur correspondent reports.

Hailing from Comilla, Rustom was on leave preparatory to retirement (LPR) since November last year, the correspondent said quoting Superintendent of Kashimpur Jail (Part-1) Subrata Kumar Bala.

Rustom was in civil dress when he was murdered, he said. "The assailants, riding a motorcycle, suddenly appeared on the scene, opened fire at Rustom and fled away."

The victim received gunshot wounds to the head and chest. He died on the spot. The body has been sent to the morgue of Gazipur Shaheed Tajuddin Medical College Hospital.

One person has been picked up from the crime scene, said Harun-or-Rashid, Gazipur superintendent of police.

Inspector General of Prisons (IGP) Brig Gen Syed Iftekhar Uddin admitted that a murder "so close" to the proximity of the prison is "of great concern to the police and the general public."

He added that the jail authorities all over the country have been instructed to beef up security.