The National Weather Service issued a bulletin saying a "confirmed large and extremely dangerous" tornado had struck near Indianapolis, the state's capital and largest city, as severe storms rolled through the region in the late afternoon.
The Weather Service also reported that a Starbucks coffee shop was demolished in Kokomo, a city of 45,000 people about 60 miles (97 km) north of Indianapolis, but said there were no immediate reports of anyone hurt.
Video footage apparently shot with a cellphone through the window of a bar across the street and aired by Indianapolis-based NBC News affiliate WTHR-TV showed the entire front wall and facade of the Starbucks collapsing in the wind.
Aerial footage of Kokomo broadcast by WTHR also showed a five-block residential area where at least 10 homes were largely obliterated and several others heavily damaged by the storm.
Indiana State Police Sergeant Tony Slocum said in a Twitter message that "numerous structures" were damaged in Kokomo, with an unspecified number of "minor injuries" reported in surrounding county.
AccuWeather.com reported that two severe thunderstorms had produced tornadoes, one just northwest of Indianapolis and the other in the Kokomo area, which according to media reports appeared to have borne the brunt of the storms.
Television station WLS-TV in Chicago, an ABC News affiliate, reported that at least five tornadoes had struck Indiana, hitting the towns of Kokomo, Arcana, Geneva and Crawfordsville.
WTHR reported that in addition to the flattened Starbucks, a tornado had caused substantial damage to a shopping mall. Footage posted on the station's website showed a dark, swirling storm with flashes of lightning as cars passed by along wet roads in the area.
Photos posted on social media showed homes with siding ripped off and scattered debris in yards. Another photo showed a barn reduced to rubble.
Indiana Governor Mike Pence, the Republican vice presidential nominee, tweeted: “Keeping Hoosiers and first responders in our prayers as dangerous weather moves through Indiana.” His Twitter page said he was leaving the campaign trail to return to Indiana.
More than 22,000 customers were without power north of Indianapolis, Duke Energy reported. Another utility, the Indianapolis Power and Light Company, said roughly 11,000 customers were without electricity in the afternoon.
Howard County emergency management and sheriff's office officials said they were gathering information on the extent of damage in the area and whether there were any casualties.
The county issued a state of emergency to remain in effect until 9 p.m. EDT (0100 GMT Thursday).
Tornado warnings were issued before 3 p.m. as a storm moved through Boone and Montgomery counties, including Crawfordsville, a city of some 16,000 residents about 50 miles (80 km) northwest of Indianapolis.
Banner and thumbnail credit: Reuters, John Sommers