A seven-year-old boy died and at least 39 others suffered burn injuries after air conditioners burst at the Baitus Salat Jame Masjid in Narayanganj's Sadar upazila after esha prayers last evening.

Fire officials suspected a gas leak caused the incident.

Dr Samanta Lal Sen, coordinator of the Sheikh Hasina National Institute of Burn and Plastic Surgery, confirmed to that a seven-year-old boy named Jewel died after being admitted with 95 percent burns. The 39 injured have been admitted to the institute for treatment, he added.

Most of the patients were admitted in the institute with major burns on their bodies, he said, adding that condition of many patients is critical.

Prof Dr Abul Kalam Azad, director of the institute, said around 35 admitted patients are suffering from 60 to 70 percent burns.

The incident occurred around 8:45pm at Pashchim Talla Baitus Salam Mosque. Hajiganj Fire Service and Civil Defence station's officer Morshed Alam said according to locals many have suffered burn injuries in the incident.

Rahmatullah Chowdhury, in-charge of Bomb Disposal Unit of the Counter Terrorism and Transnational Crime (CTTC) Unit, told The Daily Star that primarily they found that the explosion took place from the air-conditioner.

"But we are analysing the information and a team from the bomb disposal unit is also going to Narayanganj to collect evidences to find the nature and reason behind the explosion," he added.

"A gas line of Titas passes beneath the mosque. We are primarily suspecting that gas had leaked from the line and accumulated inside the mosque since the windows were shut. When the air conditioner was turned on, due to sparks the gas might have exploded," said Abdullah Al Arefin, assistant director of Narayanganj Fire Service and Civil Defence.

Enamul Haque, who lives near the mosque, told The Daily Star that he had gone to the place of worship for Esha prayers and that there was a power outage when the Imam gave his call to prayer.

There were about 120- 130 worshippers at the three-storey mosque, he said.

After the prayers, around 80 remained for the nawafil prayers and when the electricity came back on, all eight air-conditioners burst into flames on the ground floor, according to Enamul.

His brother-in-law, Mizanur Rahman, was one of those injured.

The Narayanaganj fire service was soon at the scene, and took the injured to Dhaka, he said, adding that he also made the journey with his injured relative.

Currently, around 400 people are waiting outside the institute restlessly as updates about their injured friends and relatives are not forthcoming.