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PORTLAND, Ore. – Many people in the Portland metro area reported hearing a loud boom Wednesday night but the source of the sound remains a mystery.

It might have been a bolide meteor, which explodes brightly and can create a sonic boom.

“Shook the house in Tigard Scholls Ferry area,” Erik Wilbur tweeted to KGW. “Figured it was a small earthquake.”

KGW received reports from people in Washington, Clackamas, Multnomah and Clark counties, all saying they heard a loud noise shortly before 7:30 p.m.

There were not any reports of an explosion or earthquake in the area at that time. In fact, the loud boom reached people far beyond the metro area.

Along the Washington Coast, people reported hearing more than a loud boom. Many said they saw a bright light flash across the sky. The flash was captured on video.

WATCH: Flash of light in Grays Harbor County, Washington skies

"I live in Copalis Beach and heard a BOOM and what felt like an earthquake roll through. Also, heard the sound rolling like thunder," a resident told KING 5, KGW’s sister station.

The mystery noise and flash prompted the National Weather Service in Portland to ask NASA if there was meteor activity.

NWS Seattle theorized that it may have been a bolide meteor and “it might have hit the atmosphere [at] an angle of about 45° relative to those who heard a sonic boom.”

So it’s still not clear what exactly caused the boom or flashed across the sky. But it certainly caught the attention of many in Oregon and Washington.