Lagos, Nigeria ? Nigerian authorities opened the gates at two swollen dams in the country’s rain-soaked north, sending a flood into a neighboring state that has displaced 2 million people, officials said Friday.

Water from the Challawa and Tiga dams has swept through rural Jigawa state, bordering the nation of Niger, said Umar Kyari, a spokesman for the state governor. Kyari said the rising waters have affected about 5,000 villages in the typically arid region approaching the Sahara Desert.

“They released water indiscriminately,” Kyari said.

It wasn’t immediately clear whether residents received a warning or if anyone was injured or went missing in the flooding. Officials typically open dams seasonally in the region, but it appears far more water flowed out than residents expected.

Jigawa is home to 4 million people, so half of the state’s population has been displaced by the flooding.

Nigeria, an oil-rich nation of 150 million in West Africa, has strong seasonal rains that wash through the country. However, this year has seen particularly strong rains in the north that already have broken a dam and flowed over levees in another northern state.

Local officials had begun putting displaced families in rural schoolhouses and other government buildings out of the reach of the floodwaters, Jigawa state information commissioner Aminu Mohammed said. However, Mohammed said the water had reached the border with neighboring Yobe state.

“The flood has washed away all the farms and houses,” Mohammed said.