ABUJA, Nigeria (AP) — At least 88 people have been confirmed dead after floods submerged Mokwa, a market town in Nigeria’s Niger State, on Thursday, an official said.

Husseini Isah, head of the operations office in Minna, capital of Niger State, said that many more are still at risk, with rescue efforts underway on Friday. Earlier reports said at least 20 died.

“The number keeps rising,” Isah told The Associated Press. “But at the last count, 88 bodies have been recovered.”

The floods were triggered by torrential rains that lasted several hours. According to local reports quoting residents and local government officials, a dam collapse in a nearby town worsened the situation.

Mokwa is a major meeting point for traders from the south and food growers in the north of the country.

In a similar occurrence last September, torrential rains and a dam collapse in Nigeria’s northeastern Maiduguri caused severe flooding, leaving at least 30 people dead and displacing millions, worsening the humanitarian crisis caused by the Boko Haram insurgency.

Nigeria often faces seasonal floods, particularly impacting communities along the banks of the Niger and Benue Rivers.