Hours after a ferocious fire wiped out a section of downtown Madelia, Minn., on Wednesday, appeals for help popped up on social media and elsewhere, generating tens of thousands of dollars in donations.

At least eight Main Street businesses were taken out by the blaze, said City Administrator Jane Piepgras. The fire may have been sparked by an explosion about 3 a.m. in one of the damaged buildings, according to a witness. No deaths or injuries were reported.

A hair salon, restaurant, upholstery shop, an insurance office, a dentist's office and others were damaged or destroyed, said Karla Angus, director of the Madelia Area Chamber of Commerce. The city has roughly 2,200 residents and is about 25 miles southwest of Mankato

The cost to rebuild the city will take days or even weeks to calculate, but a disaster recovery grant from the Southern Minnesota Initiative Foundation, an economic development nonprofit, quickly raised $30,000; it may grow to $50,000 or more, said organization president and CEO Tim Penny.

"They are losing at least eight businesses on Main Street. If you're a small-town guy like I am, that just hits you hard," he said.

His organization's pledge of $15,000 was matched Wednesday by AgStar Financial Services, a Mankato cooperative.

The fire may have been sparked by an explosion about 3 a.m. Wednesday. No one was killed or injured.

A spokeswoman for AgStar said the organization was challenging other organizations and corporations to match its donation.

Meanwhile, a "Rebuild Madelia's Main Street" page on the website GoFundMe had raised more than $7,000 by Wednesday evening.

Another page, "Krystal and Daniel Rebuild After Fire" had raised more than $5,000 for the reconstruction of La Plaza Fiesta, a popular Mexican restaurant.

Among the shops damaged was Hope and Faith Floral, which opened for business in 2008. It is owned by Ryan Visher, who is a Madelia firefighter and was among those who answered the fire call, a city official said. The shop's name is taken from the middle names of Visher's daughters.

Flames reached many businesses in the block, said Piepgras.

She estimated that the damaged shops made up two-thirds of the block. "They're all taken down," she said.

As daybreak arrived Wednesday, rubble covered the sidewalk in front of a destroyed building on the north side of Main Street.

"There's so much smoke, you can't even see down the street," said Jeff Van Hee, who witnessed some of the fire from his office at the Madelia Times-Messenger newspaper, which he owns. "The street's got a lot of water and ice on it from putting the fire out."

Piepgras said the fire is "going to have a devastating impact on our community. It's just been chaos around here."

CenterPoint Energy turned off natural gas service in the area as a precaution, she said.

Along with Madelia Fire Department personnel, crews were on the scene from Butterfield, Hanska, Lake Crystal, La Salle, Lewisville and St. James.