The cloud was spotted by thousands of Hoosiers who gathered to watch a fireworks display in downtown Indianapolis, and many RTV6 viewers from Shelby, Hamilton, Johnson, Hancock, Hendricks, Putnam and Delaware counties also said they saw the cloud.

Slideshow: Download: Storm Shield

RTV6 Meteorologist Todd Klaassen said the odd-shaped cumulonimbus cloud is often seen during thunderstorms, and that rain fell briefly in Shelby County. What made it stand out was the fact that it was the only cloud in the sky for most people.

The Storm Shield app showed a small thunderstorm over southern Shelby County at the time. The storm was slow-moving and covered a very small area.

Some RTV6 Facebook fans said they saw lightning coming from the cloud as sunset neared.

“We saw it from Plainfield, lots of lightning within the cloud,” Charlotte Whitney Ferrill said.

“Saw it in Plainfield! Lightning behind it, then the bright moon came out!” Nancy Kasnak Lee said.

Other RTV6 viewers didn’t know what to make of the strange-looking cloud.

“I saw it from Clay County. Weird, like Indy was hit by a nuke or something. Wow!” Roger LaPlante said.

“I saw it in Cloverdale last night around 9:30 p.m. and mentioned to my husband. It looked like a bomb mushroom cloud,” said Trisha Shrum Shrader.

One RTV6 fan thought the cloud made a timely appearance.

“(It’s) the 'Independence Day' (movie) cloud,” Connie Collins McClure said.

Watch RTV6 and refresh this page for updates.