EVERETT, Wash. -- KIRO 7 viewers in Snohomish County are complaining of a mysterious, overpowering odor that's stinking up their neighborhoods and making some people sick.

The stench has been on the mind of people who live in the Sunnyside neighborhood of Marysville and some said they found the smell so sickening that they called 911.

"At its worst, it smells like a herd of cows with diarrhea of the worst kind, like after they ate a bunch of chemicals," said resident Jennifer Parkinson.

State investigators with the Puget Sound Clean Air Agency told KIRO 7 reporter Gary Horcher they followed the odor and believe the foul smell is coming from a compost processing plant in North Everett.

Cedar Grove Compost declined to talk to KIRO on camera, but investigators plan to meet with company representatives to find out what is causing the stink.

Resident Wendy McKenna said odor is making her so sick that she's had to leave her home to get fresh air.

McKenna said she's considered moving away from the view she loves to elude the stink.

"I could taste it on my tongue it was so bad and my chest felt heavy like I couldn't get a lung full of air," said McKenna.

Neighbors who complained to the state said they were unaware until Monday that the problem was being investigated.

Investigators are meeting with the company on Wednesday.