ABUJA, Nigeria (AP) — More than 50 people were killed and many injured when an explosion rocked an illegal oil refinery in southeastern Nigeria, state officials and police said Saturday.

The death toll may be more than 100, according to a report in the Lagos-based Punch newspaper. The fire was reported to have spread to nearby properties.

The fire broke out Friday night and quickly spread to two fuel storage areas at the illegal crude oil refinery, causing the complex to be “engulfed by fire which spread rapidly” within the area, said Declan Emelumba, the Imo State commissioner for information.

The immediate cause of the explosion and the extent of the deaths, injuries and damage were being investigated, Emelumba said.

Multiple videos posted on social media showed a gruesome scene, with people’s charred remains reduced to skeletons and cinders. The Associated Press was unable to independently verify them.

“A lot of people died. The people who died are all illegal operators,” said Michael Abattam, spokesman of the Imo State Police Command.

The Imo state government was looking for the owner of the refinery where the explosion occurred and declared him a wanted individual, an official said.

Illegal refineries are common in Nigeria, where shady business operators often avoid regulations and taxes by setting up refineries in remote areas, out of sight of authorities.

Nigeria is Africa’s largest producer of crude oil but it has very few official refineries and as a result most gasoline and other fuels are imported, creating an opening for the illegal refinery operators.

The practice is so widespread that is affecting crude oil production in the oil-rich Niger Delta region.