A very loud "boom" rattled many people in parts of Great Falls on Wednesday night.
The noise was heard at 10:54 p.m., and people reported hearing it on the southwest side of town, east of downtown, and along the northwest side.
Most people believed the boom emanated from an area near or to the east of the Montana ExpoPark.
Speculation ran wild on social media, with many people posting on Facebook that they heard it and were wondering what it was.
Some people thought it was thunder, as there was a storm approaching Great Falls from the southwest, but most agreed that it did not sound like thunder. Others thought that it might have been a gunshot.
Several people speculated that a ride at the Montana State Fair may have malfunctioned, and some people claimed that one of the rides had broken into two pieces.
KRTV contacted the Great Falls Police Department, and they said that they had not received any reports of gunshots, and that the noise appeared to have been a large firework that was set off at or near Gibson Park.
A few minutes later, some people began asking about an apparent evacuation at the Fairgrounds; the Cascade County Sheriff's Office posted on Facebook that there was no disaster or emergency situation, but that they had requested that the Fair shut down a little bit early due to the approaching thunderstorm.
That - coupled with the end of a concert at the Fairgrounds - led to a surge of people leaving the area in a very short amount of time.
Two videos shared with KRTV reveal that it likely was a large/loud firework.
In one video - from a deck surveillance camera near Skyline Drive- the loud noise can be heard clearly, despite the residence being located more than two miles away from Gibson Park.
The second video, sent anonymously to KRTV, shows a fireworks detonation in what appears to a park, and the sound of the boom "syncs" with the sound on the first video.