Colorful origami butterflies found around Seattle displaying ominous messages appear to be connected to an anti-abortion campaign.

The folded papers, which were found this week in Capitol Hill, the U-District, South Lake Union and downtown, generated a lot of chatter on social media.

When unfolded, the message “you are not safe,” could be read along with the date 9-28-17.

The flip side of the papers had illustrations of Russell Wilson, Kurt Cobain, the Starbucks siren, and a message about peace.

As people around Seattle got wind of the messages, many speculated what they might mean.“It could be a marketing gimmick for an artist or something, I don't know,” said Henry Bridges, who found one of the papers in Capitol Hill.Some Facebook users thought the messages were some sort of marketing effort for an Insane Clown Posse concert scheduled in Seattle for Thursday. Others said the messages were tied to a band in Michigan. Some tried to look into the website's source code to see who was hosting the site.Some Seattleites said they planned to stay home from work on Thursday as a precaution.“I had some friends at Amazon say they're not going to go to work on the 28th, so, Amazon, if people aren't showing up on the 28th, now you know why,” Marc Shelffo, who also discovered one of the butterflies.

Seattle police said on Wednesday afternoon that they did not believe there were any safety concerns related to the origami, which they thought might be part of an ad campaign of some sort.A campaign called The Tenth Mark appears to be behind the messages. Its site displays the same images and YouTube videos conveying anti-abortion and religious sentiments.“Do not be alarmed. We mean you no harm. But we have come to invade your safe space,” the site reads.Links on the website for more information are directed to a group called Abolish Human Abortion.The site domain is registered through a service that protects the owner's identity.The website doesn’t address the date printed on the origami butterflies, but September 28 is recognized by some groups as a "global day of action for access to safe and legal abortion."