A group of people were seen climbing out of a Portland sewer through a manhole cover.

Kris Lake, the owner of a hardware store, started looking through security footage after he found a shoe on the sidewalk, The Oregonian reported.

>> Read more trending news

Video showed three people emerge from the manhole Thursday and change their clothes, The Oregonian reported.

Lake reviewed more footage and found video of five other people climbing out of the pipe on June 2. One of the people is seen waving at traffic. The saved recordings only go back to June 1.

"I don't know how many people would want to go to a sewer manhole, but it's an inherently unsafe place to be," Diane Dulken, spokeswoman for Portland's Bureau of Environmental Services, told The Oregonian.

Lake said he was asked about a year ago if someone was living in the sewer after a delivery driver noticed the manhole cover appeared to have been moved.

"Maybe he was onto something," Lake told The Oregonian. "Now, we have proof it's been happening."