Dozens of rats have been found dead inside an Ottawa Fire Station in Riverside South, only a week after the station was shut down because of rat troubles .

As many as 50 rats were discovered at Fire Station 37 on Earl Armstrong Road on Tuesday alone. One photograph sent to CTV News shows 19 rats spread out on the curb outside the building.

Firefighters say they suspect the infestation could involve hundreds of rats. Fire officials say the station may need to be closed again to deal with the infestation.

"We shut it down briefly when the issue first arose because of concerns, and we may have to do that again," deputy chief Kim Ayotte said.

More than a week ago, as many as 30 rats were found on the premises. The building was evacuated over the weekend, and firefighters returned on Tuesday.

Ayotte said any firefighters who don't feel safe working out of the building can be deployed in "dynamic mode," meaning they're deployed on a truck that stays in the neighbourhood.

The city says the hole the rats are in is a vestibule area, not near the firefighters' sleeping quarters, and there's no danger to the workers' health.

"We have no concerns based on what the environmental engineers found in air quality, and what we've found with the work today" city area manager of facilities David Barkley said.