At least six people have died in Indiana after a powerful storm system brought more than 11 inches of rain to parts of the US state, triggering historic flooding and widespread rescue efforts, according to authorities.

Flooding was concentrated along the White River from Hamilton County into the northern Indianapolis suburbs, where more than 90 people and 45 pets were rescued, NBC News reported on Saturday.

In Indianapolis' Ravenwood neighborhood, floodwaters submerged cars and reached the doors of homes as residents used kayaks and rowboats to move through the streets.

Gov. Mike Braun said he had spoken with President Donald Trump and that an expedited Federal Emergency Management Agency declaration was being processed, the report said.

"My heart is with the families and loved ones of the five Hoosiers we have lost and every family whose life has been changed by these storms," Braun said. "Please continue to take flooding seriously and stay away from floodwaters."

The National Weather Service said some areas received more than 11 inches of rain over two days. The White River rose above 24 feet in Anderson and Noblesville, surpassing records set in 1913. Indianapolis Mayor Joe Hogsett urged residents along the river to evacuate after declaring a local emergency.

"This is one of those once-in-a-lifetime type floods," said Jacob Spence, director of Marion County Emergency Management. "So, yeah, this is an unprecedented event and unfortunately we're setting some new records."

Another storm-related death was reported in Delaware County, where a 58-year-old woman was found dead after apparently attempting to drive through floodwaters. Indiana Department of Homeland Security spokesperson Liz Woods also confirmed the fatalities in Jennings, White, Porter, and La Porte counties.

Flash flood warnings remained in effect across central Indiana, with more storms expected. "The water is still rising, so heed the warnings," said Todd Wilson, director of Indianapolis' public works department.

The storms also caused tornadoes, heavy rain, and flash flooding across the Midwest, with damage reported from the Chicago area to western Pennsylvania. (Anadolu Agency)