Plastic explosives planted in another cinema did not explode, local district administration said, adding the twin attacks within five minutes from each other bore similar hallmarks of militant violence.

The explosions evoke the memory of closely-timed Mymensingh cinema blasts on December 7, 2002 that killed at least 18 people and injured many more and Roxy Cinema explosions in Satkhira on September 28 the same year that killed three and injured over 150 people.

The Sylhet cinema explosions come in the wake of a blast at the shrine of Hazrat Shahjalal on January 12 that killed five people and a second bomb attack on May 21 that killed three people and injured many others including British High Commissioner to Bangladesh Anwar Choudhury.

The explosion at Rangmahal cinema blew off the left leg of the boy who died instantly.

Six of the injured are Zakir Hossain, Anwar Hossain, Babar Ahmad, Zakir Mia, Shahin Hossain and Monica. All of them are being treated for injuries at Osmani Medical College Hospital. Some of the injured are being operated upon, a hospital source said.

The first explosion at the ticket counter rocked Monica cinema at Bagbari at 9:00pm, injuring Suleman and an unknown man.

Some local residents suspect Suleman was the carrier of the bomb, but the claim could not be probed immediately.

The second blast at the narrow main gate of Rangmahal Cinema at Bandar Bazaar, 4 kilometres off Monica Cinema, five minutes later also left six injured.

Members of a Directorate General of Forces Intelligence (DGFI) team retrieved plastic explosives from a bag near the ticket counter of Abokash Cinema in the city's Taltola area left behind by a man who bought a betel leaf from a vendor there.

Alarmed by the unclaimed bag, the stallholder informed the cinema authorities of its presence and the authorities informed the intelligence agency.

Police raided several areas after the explosions and picked up seven people for interrogation.

Witnesses said they saw congealed blood, flesh, sandals and other belonging of people strewn all over.

"I heard a big bang and my wall clock fell on the floor and glass of the almirah broke in vibration," Abdul Hai, owner of a shop in front of Rangmahal Cinema, told The Daily Star.

"As I stepped out of my shop, I saw the 10-year-old boy groaning just in front of me."

"The explosion also scattered cigarettes, small boxes and containers from stalls adjacent to my shop."

Uniformed and undercover police and intelligence personnel were deployed in all three cinemas and police cordoned off the blast site.