Police are investigating a suspicious envelope found at the Whole Foods Saturday afternoon near Westlake Avenue and Denny Way.
Eyewitnesses told KIRO 7 there may also be a strange connection to a protest against Monsanto, a company that produces genetically modified organisms.
A Hazmat team responded to the location. According to the Seattle Fire Department, two envelopes were found, but only one had an unknown substance leaking from it that smelled like rotten eggs.
As a precaution, the store was evacuated. Eventually, Hazmat crews found out the substance was not harmful. However, an eyewitness inside the store said writing on the envelopes indicated they might have been left by someone participating in the protest earlier in the day against GMOs.
The potential connection baffled a Whole Foods spokesman.
"If that were to be the case, it would be even more tragic," he said. "We're a strong supporter of transparency in food. Whole Foods has made a declaration, the only grocery in the country, to say we're going to label all genetically modified foods by 2018."
A Seattle police spokesman on the scene would not say whether officers are investigating protesters.
Around 3 p.m., the store reopened.