The cause of a fatal building fire in Beijing was found to be caused by a malfunctioning electric tricycle that was stored in the building, said an official from the Beijing Municipal Public Security Bureau on Tuesday.

Those suspected of criminal negligence in relation to the fire have been detained, the official said.

The fire broke out around 1 a.m. Monday in a building in the town of Jiugong in Beijing's Daxing district, killing 17 people and injuring 25 others.

At least seven people, including two children, are still in critical condition.