A Toronto flea market owner where a rabid dog was sold says he feels bad the incident has prompted worries and a health alert, and has called the ordeal an unfortunate incident.

Allen Koffman says it is the first such incident at Dr. Flea's Flea Market, which has been in operation for 20 years. The business is located at Highway 27 and Albion Road.

Koffman says the vendor who sold the infected puppy runs a clean operation.

"He's been here for a year-and-a-half. He's sold probably well over 300 dogs, and has made a lot of people happy," Koffman told CTV Toronto.

"It's an unfortunate situation that has happened. He feels very badly about it, and we feel very badly about it."

Koffman and his 17-year-old son are among the 20 people in Toronto receiving rabies vaccinations because they came into contact with pets at the booth, which had a "Pets R Us" sign posted on it.

Toronto Public Health said they have received more than 500 phone calls since they issued a rabies alert on Wednesday.

The agency believes they have located most of the puppies that were being held with the rabid dog, which was sold on Jan. 13. The infected puppy and one other dog in the group have died.

On Thursday, health officials once again urged residents who may have visited the booth recently, or purchased a pet there, to contact their doctor

Rabies can be fatal if left untreated. Flu-like symptoms are often the first signs of rabies in humans.

So far, there are no known human cases linked to the flea market incident.

Meanwhile, health inspectors have set up a booth at the flea market and will be there all weekend to answer people's questions and spread the word about the incident.

With a report from CTV Toronto's Alicia Kay-Markson