A fire ignited as people were scavenging spilled fuel from an overturned tanker truck in northern Nigeria, killing 70 and wounding 20, an official said Wednesday.

The truck was carrying about 8,700 gallons of fuel when it overturned on a curve in the road late Monday in northern Kaduna state, said Saad Yahaya, a police spokesman for the region. The driver told passers-by not to collect fuel gushing from the disabled vehicle, but they ignored him, Yahaya said.

It wasn't known what caused the fuel to ignite, he said.

Nigeria is Africa's largest producer of crude oil, but years of corruption and mismanagement have left the country's refineries in tatters and shortages of fuel for vehicles and cooking are common — as is the tapping of fuel pipelines.

In December, fuel spewing from a broken pipeline caught fire as people were scavenging it in Lagos, Nigeria's biggest city, leaving 265 dead.

Last year, 150 people died in a similar incident, and a 1998 pipeline fire killed 1,500.

Many Nigerians feel they have gained little from decades of oil production in their country, saying gas flaring and oil spills have polluted their lands while they remain largely impoverished.