Dhaka, Jul 2 (IANS): At least one person, possibly a foreigner, has been freed after Bangladeshi security forces started an operation to free up to 40 hostages taken by about eight to nine gunmen who attacked a restaurant in the diplomatic quarter of Dhaka.

In an attack claimed by the Islamic State militant group, the gunmen reportedly took up to 40 hostages and killed two police officials in a cafe in Dhaka late Friday, RT.com reported.

Bangladeshi Rapid Action Battalion (RAB) have started an operation to free the hostages, the report said.

After hours of quiet, a fresh round of heavy gunfire took place on Saturday morning, an eye witnesses told CNN.

Fayad Munaim, who could hear intense gunfire coming from the direction of Holey Artisan Bakery, said the shots lasted about 10 minutes. Then the barrage stopped.

As the police exchanged fire with the gunmen, the attackers threw explosives, a source at the scene told CNN.

The IS group claimed that its gunmen killed 24 people and injured 40 others in the attack late Friday.

Meanwhile, security forces in Dhaka clarified that only two police officials were killed and at least 15 people were injured.

Chief of the Rapid Action Battalion Benjir Ahmed said "derailed youths" entered the restaurant and launched an attack.

"One of the attackers was armed with a sword, the others carried guns," an employee of a nearby cafe told RT.com.