(Photo: Xinhua)

Beijing on Monday ruled out the possibility of arson in an apartment fire that killed 19 people, announcing that it was caused by an electric wire fault.

The fire broke out on the evening of Nov. 18 at a three-story apartment in Xinjian Village in the city's Daxing District.

The public security bureau Daxing branch has detained 20 people allegedly liable for the fire.

An investigation showed that one of the suspects, surnamed Fan, built the 20,000-square-meter apartment bloc between 2002 and 2006 without approval from authorities.

In February this year, Fan started to build an underground cold storage basement, and invited some unqualified workers to equip the freezer with electric wires.

The fire broke out from a wall of the freezer, where electric wires buried in polyurethane insulation material had broken down, according to investigators.

The freezer had not been put into use and was being tested when the fire occurred.

The police are continuing to investigate the case.