It's one of Toronto's most popular Chinese restaurants, but on Wednesday those walking by Happy Seven were given plenty of reason to feel sad - and scared.

Despite passing a health inspection just days earlier, the Chinatown establishment and fixture of the Spadina strip was home to a least three rats, running free inside the dining room for customers - and CityNews cameras to see.

Happy Seven management wouldn't speak to CityNews on camera, but Toronto Public Health was notified and promised an investigation. Should their people find any proof of rodent infestation the restaurant would be closed immediately.

"If you find rodents walking around the kitchen with rodent droppings possibly contaminating cooking surfaces that is an immediate potential health threat and we would shut a restaurant down," promised TPH Chair John Filion.

But that's not an option Filion and his crew has. They scoured the restaurant late Wednesday afternoon and reportedly found no evidence of a rat infestation, meaning they have no authority to shut the place down even after watching our video evidence.

"No rat droppings, no problem whatsoever with compliance with public health standards," Filion told Andrea Piunno Wednesday night. "It's kind of a mystery."

And until that mystery is solved with the official discovery of some vermin on the premises, the restaurant and countless business around it remain open to the public.

Of course in the big city the threat of rats, mice and issues of general cleanliness lurk around every corner.

If you see a health code violation in any restaurant, you can report it to Toronto Public Health.