Oregon - Emergency dispatchers in the Portland area received several reports of a loud boom Sunday evening.
The FOX 12 newsroom also received numerous calls from people reporting what sounded like an explosion. The reports came from as far east as Boring and as far north as Vancouver.
The source of the boom is unknown. Jim Todd, of the Oregon Museum of Science & Industry, said the explosion was likely not a fireball.
"Certainly a fireball can produce such an explosion and be heard for miles in cloudy conditions," Todd said in a news release. "What is missing is the positive visual sighting reports."
Todd said radar has yet to reveal a fireball.
The Portland International Airport did not report anything in the area that would have created a sonic boom.
Representatives with the United States Navy and the Oregon National Guard also said they had no information on what may have caused the noise.
Fort Lewis Army Base and the McChord Air Force base were also unaware of anything that could have created the boom.
Many local Twitter users
have speculated on what may have caused it.