Updated: 3:48 p.m.
Authorities in northern Minnesota say they’re not sure what caused a bright flash and “incredibly loud explosion” that shook buildings across parts of the region Monday evening.
Initial speculation was that it could have been a meteor — but officials and experts said Tuesday that further analysis of the evidence suggests that may not be the case.
Beltrami County Emergency Management Director Christopher Muller reported it happened at about 6:40 p.m. Muller told MPR News on Tuesday that he was among the Bemidji-area residents who heard it. He had just returned home from a walk with his dog when the blast happened.
His dog was outside “and I was wrapping up some tasks in the house and all of a sudden heard a very loud boom. It was so loud that it actually rattled (the) windows of my house. And about two seconds later, the dog was at the door trying to break in because it scared him so bad,” Muller said.
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The blast prompted a flurry of 911 calls to Beltrami County dispatch. The flash of light and subsequent blast reportedly were seen or heard in the Bagley and Blackduck areas, too. Bagley is about 20 miles west of Bemidji; Blackduck is about 20 miles northeast.
Sheriff’s deputies and police officers began to check the area after the blast.
“We checked all the power substations; there were no power outages reported, which you would expect if it were a transformer, a substation or something of that nature — but we didn’t get any reports on that,” Muller said.
Muller also said the speed of the light and magnitude of the sound were much greater than what’s caused by Air Force jets that sometimes fly over the area from Grand Forks, N.D. Weather radar didn’t detect anything unusual over Bemidji at the time of the blast.
There were no reports of damage or injuries.
A resident of the Nymore section of Bemidji shared home surveillance video that captured the blast; county authorities shared that video with the public. They also shared a second video from Bemidji Regional Airport that shows the flash of light streaking across the sky; the second video does not include audio of the blast.
The cause of the flash and boom remained unclear as of Tuesday afternoon.
In an update, Muller said experts examined the two surveillance videos and “determined the object is too horizontal to indicate it was a meteor.”
Robert Lunsford is a fireball report coordinator with the American Meteor Society, which collects reports of meteor sightings across the country. He told MPR News there are a couple of active meteor showers underway — but the timing between the flash and the sound in Bemidji would appear to make a meteor unlikely.
“It’s possible that it’s a meteor, but ... at an altitude of 25 miles, it takes sound at least 30 seconds to normally reach the ground depending on how far it is from the observer. So the three-second difference between the flash and the sound (in the Bemidji incident) kind of leads me to believe it was something a lot closer,” he said.
Lunsford said the society has been gathering reports of meteor sightings for nearly 20 years.
“The reason we’re really interested in tracking these fireballs is they’re a source of the material from outer space,” he said. “We’ve used these reports to actually track down some meteorites that landed on the ground.”
Back in Minnesota, Muller in his Tuesday afternoon update said the county appreciates “the assistance we’ve received from federal agencies and (the) science community in ruling out what it wasn’t. (Local officials) will continue to provide any subsequent information that is learned,” he said. “The fact (that) this was seen and heard across such a large area is what is a mystery. What was it?”