Three children who were found dead under unclear circumstances on Friday died after inhaling poisonous gas in Matlab Dakkhin upazila of Chandpur, according to autopsy reports.
Three Bhangarpar Madrasa students were found unconscious in a small room adjacent to the mosque after Jumm'a prayers, reports news agency UNB.
Two of them died before they could be taken to the hospital. Another boy died minutes after he was hospitalised.
Chandpur police chief Jihadul Kabir said the room was too small and had no window. Poisonous gas was produced by three IPS batteries in the room.
The children fell sick after inhaling the gas and died, he said.
The deceased were Abdullah Al Noman, 10, son of Purbokaladi Jaam'e Masjid's Imam Maulana Zamal Uddin; Ibrahim, 10 of Bhangarpar village; and Rifat, 8, son of Jasim Uddin of Nalua village.