At least 46 people died and 41 were injured after fire engulfed a 13-storey building in Taiwan’s Kaohsiung city in the early hours of Thursday, AP reported.

The authorities are yet to ascertain the cause of the fire. However, witnesses told the local media that they had heard a loud explosion before the fire.

The blaze was “extremely fierce” and destroyed many floors, AP reported, quoting the Kaohsiung fire department. It took the firefighter four hours to douse the fire at the residential building.

The fire officials took 79 people to hospital, of which 14 are in a serious condition, BBC reported. The firefighters also said that some citizens were feared to be trapped on the 11th floor of the building.

The fire department said that clutter on the lower floor made the rescue operation difficult. The department urged the citizens to not allow unused items to accumulate around their homes. The building’s lower floors once housed restaurants, karaoke bars and a cinema, but these were no longer in use.