At least 30 people died, and a million others were affected by heavy flooding in Nigeria's northeast, emergency services said Wednesday.

"The death toll is 30," National Emergency Management Agency (NEMA) spokesman Ezekiel Manzo told AFP a day after water from an overflowing dam swept away thousands of homes in the capital city of Borno state.

"The situation in Maiduguri is quite frightening," said Manzo's NEMA colleague Zubaida Umar.

"The flood has taken over around 40% of the entire city. People have been forced out of their homes and are scattered everywhere.

"From our statistics, we have 414,000 displaced people," said Umar, adding that authorities feared the total number of displaced could hit one million.

Umar added the city's main hospital had also been affected by flooding which the U.N. refugee agency in Nigeria said on X Tuesday was the city's worst flooding in 30 years.

According to NEMA, more than 23,000 households, and upwards of 150,000 people, have been hit by the rapid rise of waters following the weekend rupture of the Alau dam on the Ngadda River, 20 kilometers (12 miles) south of Maiduguri.

An estimated 1 million people have been affected by heavy flooding in Maiduguri, a government official said.

Babagana Zulum, the governor of Borno State, told journalists the estimate was based on a preliminary assessment conducted by the government after the flood hit Maiduguri on Tuesday and caused devastation, the worst in three decades.

"The floods covered one-third of the city, affecting over 1 million people. It is very devastating," Zulum told journalists while distributing cash and food to thousands of displaced persons at a camp.

He said over 100,000 people are displaced, even as search and rescue efforts continue.

"We are distributing money and food to head of each of the families as a temporary measure to cushion the impact," he said, adding that the government plans to constitute a health team to prepare a response for possible emergencies after the waters recede.

He also blamed the collapse of a dam in the city's outskirts and the overflow of water released from neighboring African nations of Niger and Cameroon for the situation.

The flood washed away animals at zoo, and damaged houses, schools, hospitals, government offices, as well as commercial centers and worship centers.