A boiler exploded and triggered a fire at a packaging factory near Bangladesh’s capital on Saturday, killing at least 21 people and injuring dozens, officials said.Several bodies were recovered from the Tampaco Foils factory in the Tongi industrial area outside Dhaka, fire official Mohammed Rafiquzzaman said. Mohammed Parvez, a doctor at Tongi Hospital, said 17 dead bodies were in the hospital’s mortuary and four were at the state-run Dhaka Medical College Hospital.

Fire officials working at the scene said that the explosion was huge and that the fire triggered by the blast spread quickly because flammable chemicals were stored at the factory.

Local TV stations said about 50 people were injured in Saturday’s disaster, indicating that the death toll could be higher. Television footage showed smoke billowing from the factory, with the fire engulfing part of the upper floors.

It was not immediately clear what caused the explosion. Authorities have ordered an investigation.

Syed Mokbul Hossain, the owner of the Tampaco Foils factory, told the Bengali-language Prothom Alo daily that he was not sure when the boiler was last inspected.

In 2012, a fire at a garment factory in a Dhaka suburb killed 112 workers. A year later, a commercial complex near Dhaka housing five garment factories collapsed, killing 1,135 people, Bangladesh’s worst industrial disaster.

The accidents prompted Bangladesh’s government, global brands and the United Nations to work together to try to improve safety standards in the South Asian country’s factories.