At least 11 people, mostly women and children, were killed in Bangladesh in a fire that broke out early morning Sunday in one of the biggest slums in capital Dhaka.

More than 500 homes were gutted in the fire that engulfed the Bou Bazar slum, home to low-income people such as day laborers and rickshaw pullers, at Hazaribagh in the outskirts of Dhaka at around 3 a.m. Charred bodies of six women, four children and a man were found, while seven people were sent to the hospital with severe burns. Scores of others have sustained serious injuries, news agencies reported citing Bangladeshi officials.

The cause of the fire was not immediately known, though initial reports indicate that a cigarette or mosquito repellent coil may have led to the accident as the homes were mostly shacks made of tin, bamboo and plastic sheets.

Prime Minister Sheikh Hasina mourned the deaths and directed quick assistance, including food, clothing and necessary goods, to the victims.