Residents in parts of Washington and Oregon have seen a mysterious substance falling from the sky that people describe as white and ashy. Its origin, however, remains a mystery.

In a statement, officials from the Washington state's Walla Walla County Emergency said that they have received reports of the substance covering vehicles and that the ash probably originated from Volcano Shiveluch, a hyperactive volcano located in Russia's Kamchatka peninsula.

The volcano released a 20,000-foot ash plume in late January, and this was deposited in a wide area that covered the states seeing the mysterious ash shower. Experts also said that although the substance could be ash from Volcano Shiveluch, there are also a number of other volcanoes from other parts of the globe that are active.

CNN meteorologist Derek Van Dam said that the substance may have been brought from an active volcano located in southwest Colima, Mexico, which erupted on Wednesday, Feb. 4. He also said that there is another active volcano in Eastern Russia. The Mexican volcano is located over 2,000 miles away from the areas of Washington and Oregon while the Russian volcano is 4,000 miles away.

"The strong southerly flow from the jet stream could have brought it from an active volcano in southwest Colima, Mexico," Van Dam said. "But if we go farther west towards eastern Russia, there's another active volcano there."

Other theories also explored the possibility that the strange substance originated from something else. One theory, for instance, points at dust that was picked up by the wind. It is also possible that these were leftover ash from the wildfires that occurred last year in Oregon and Idaho.

The U.S. National Weather Service Spokane Washington said that although there are a number of speculations on the origins of the substance, where it really came from remains a mystery. Experts said that the best way to definitely know what it is would be to conduct scientific tests.

"We are continuing to investigate and have reached out to other offices for assistance in recreating atmospheric flows from the past several days," the agency wrote on its Facebook page. "We've also reached out to other agencies that may have collected samples appropriate for testing."

Keen on knowing what the substance is, residents in affected areas have also been filling up glasses of the strange substance. The NWS said that reports of the milky rain have been received from over 15 cities and that it has already collected water samples that will be sent for laboratory testing.

ⓒ 2021 All rights reserved. Do not reproduce without permission.