Heavy rain overnight in Detroit caused flooding and has partially blocked access to Detroit Metropolitan Wayne County Airport, the airport said.

"Currently, travelers cannot access the McNamara Terminal due to flooding in the Dingell Drive tunnels. Customers with flights operating out of the McNamara Terminal are encouraged to contact their airlines with any questions about their flight status," the airport said.

Nearly three inches of rain fell on the airport over about five hours, according to the National Weather Service.

According to FlightAware, 15% of flights originating in Detroit have been delayed and 9% have been canceled, while 9% of flights heading to Detroit have been delayed and 8% have been canceled.

Detroit Metropolitan Airport (DTW) is a major hub for both Delta and Spirit and has more than more than 1,100 flights per day, according to its website.

This is a developing story that will be updated.