People in the McHenry area heard what was described on social media as a loud booming sound the evening of Thursday night. Some said it shook their homes; others reported seeing a flash of light.

McHenry police Cmdr. Nicholas Clesen said Friday the department received some calls about the loud noise and also saw social media posts about the strange occurrence at about 8 p.m. on Christmas night. Hundreds of people were commenting and asking questions about it on Facebook, and at least one user posted Ring camera footage that captured the sound.

“Our officers checked the areas where people reported hearing it come from, but were unable to find anything which would explain a noise like that,” Clesen said.

He said the department did not get any reports later Thursday night or into Friday of any incidents that could explain the noise, like a transformer explosion or traffic crash.

At the McHenry Township Fire Protection District, Acting Battalion Chief Todd Robel said the department did not get any calls about the boom noise and added he wished he had something better to share. Robel said it was a normal day for the fire department.

McHenry County Sheriff’s Office officials said they didn’t receive any noise complaints Thursday night.

Crystal Lake police officials likewise said they didn’t get any calls about a boom noise, and Richmond Township Fire Marshal Scott Peterson said the department had “no dispatches or reports of any type of sound, boom, explosion or an investigation of any type.”

A person who picked up the phone at the McHenry County Emergency Management Agency Friday said the agency had not had any calls or responses and didn’t hear anything with regards to the boom. An Illinois Emergency Management Agency spokesperson said Friday the agency had not been notified of anything like it when asked about a boom sound near McHenry Thursday.

Media contacts at the Federal Aviation Administration were on a holiday Friday, and a Great Lakes Naval Base spokesperson did not immediately respond to an email.

A spokesperson for the Illinois National Guard said it would not have been the source of the noise. The spokesperson said the Illinois National Guard doesn’t have any aircraft that can break the sound barrier, so none could produce a sonic boom. The spokesperson added there weren’t any Army National Guard operations in the McHenry area that would create a boom, and no units were conducting training Thursday or Friday.

While the source of the boom remains unclear, weather also doesn’t appear to be the explanation either.

It was too warm Thursday for a frost quake, Kevin Doom, a meteorologist with the National Weather Service, said Friday. Doom said temperatures need to be around or below 0 degrees for a frost quake to happen.

A frost quake is a “seismic event caused by a sudden fracturing or cracking of frozen soil or rock which had been recently saturated with water or ice,” according to a previous Shaw Local report.

Doom said the weather bureau had not received any calls or reports regarding a boom noise in the McHenry area Thursday evening and said he guessed it was not weather-related.