Thousands of residents were being evacuated in Michigan Wednesday after two dams failed following heavy rains and triggered what officials warned will be "historic" flooding.

Governor Gretchen Whitmer declared a state of emergency in Midland County, site of the breached dams in Edenville and Sanford in the central part of the state.

"Residents in the area have been instructed to evacuate immediately," Whitmer said late Tuesday in an address from the state's emergency response centre.

The National Weather Service warned of life-threatening flash flooding and urged people in the area to seek higher ground at once.

The downtown area of Midland, a city of about 42,000 people, could soon be under approximately nine feet (2.7 meters) of water, according to Whitmer.

"We are anticipating an historic high water level," the governor said.

It was unclear whether there were any fatalities caused by the flooding, according to the Detroit Free Press.

The flooding disaster and the evacuation are being compounded by the coronavirus pandemic, which has forced Michiganders and all Americans to observe social distancing in order to avoid spreading the virus.

Whitmer urged those evacuating to shelters to wear face masks and maintain social distancing when possible.

Multiple rivers in Michigan -- a northern state surrounded by the Great Lakes -- had reached flood stage by Tuesday after up to four inches of rain fell in recent days, the Free Press reported.

US President Donald Trump is scheduled to travel to Michigan, an important electoral state, on Thursday to visit an auto manufacturing plant that has been repurposed to make ventilators.

The plant is in southern Michigan near its largest city, Detroit.

The president has clashed on occasion with the governor over pandemic response issues, and early Wednesday Trump tweeted his complaints about the state's vote by mail efforts.