Vehicles were left burnt out and fuel pooled on the ground in Nigeria’s Imo state on Sunday following an overnight explosion at an illegal oil refining depot.

The state commissioner for petroleum resources, Goodluck Opiah, said late on Saturday that 100 people were killed in the explosion, remarking that they were “burnt beyond recognition.”

Crude oil is tapped from a web of pipelines owned by major oil companies and refined into products in makeshift tanks.

Government officials estimate that Nigeria, Africa’s biggest oil producer and exporter, loses an average of 200,000 barrels per day of oil, more than 10% of production, to those tapping or vandalizing pipelines.

The explosion was announced by a local government official late on Saturday.

The bunkering site was in the Ohaji-Egbema Local Government Area of Imo state, located in the Abaezi forest that straddles the border of neighboring Rivers state.

Unemployment and poverty in the oil-producing Niger Delta have made illegal crude refining an attractive business, albeit with deadly consequences.