Published: Aug 14, 2013 5:08 PM EDT
Updated: Aug 14, 2013 6:39 PM EDT

CAPE CORAL, Fla. - There's a mailbox mystery in one Cape Coral neighborhood. Flyers are popping up, claiming a sex offender is living in the neighborhood, and it's scaring parents.

With our camera rolling, Bryon Johnson opened his mailbox to discover a distrubing letter.

"I'm just you know really shocked," Johnson said.

He's not the only one to get it.

"My neighbor she told me about it, and I went and checked my mailbox and found it in there, also," said one woman who didn't want to be identified.

This is what the letter said, with sections removed to protect the identity of both parties.

"Dear neighbor, your neighbor (at an address) sexually assaulted (a child) this weekend.
Please keep your children safe. God bless."

Cape Coral police say the sexual allegations have sparked an ongoing criminal investigation

Meanwhile, neighbors noticed someone driving through the area in the early morning hours. Some believe that person is the one dropping off the letters.

"I get up in the early morning, clean my house, so I saw saw someone driving around with a van with no lights on," said Johnson.

Regardless if it's true or false, the letter is upsetting to many, especially those with small children.

"It worried me a lot about it because, you know, I got my kids have to go to school and they go to surfside and catch the bus," said one neighbor.

"My son he walks home from the bus stop sometimes so, by himself, I don't know if he'll be doing that anymore," said Johnson.

According to the Cape Coral police website, there is not a registered sex offender living at the home, at this time. We knocked on the home, but there was no answer.

Putting flyers in mailboxes by hand is illegal.