Three children were burnt to death and their parents critically injured in Bhangor, on the southern fringes of the city, on Wednesday evening. The couple are battling for life at National Medical College and Hospital.

The mishap occurred when Rizia Khatun, 10, and her sisters — Rezina, 6, and Serena, 3 — were playing in the courtyard of their house, near a haystack that was under an electric wire emitting sparks. A drum of kerosene was found near the spot.

“It seems to be an accidental fire. We are not ruling out other possibilities, as the family is quite prosperous,” said Praveen Kumar, the superintendent of South 24-Parganas police.

A preliminary investigations has revealed that Ayesha Khatun had heard the cries of her three children and saw smoke billowing from the haystack.

“She informed husband Zakir Sheikh, who jumped into the fire to rescue the kids,” said an officer of Calcutta Leather Complex police station.

“Ayesha, too, jumped into the fire and the two managed to bring out the kids. Alerted by their cries, the local residents rushed to their rescue,” he added.

All five were admitted to the burns ward of National Medical College. The eldest daughter died hours later. Rezina and Serena died on Thursday morning and afternoon, respectively.