Two firefighters were taken to hospital as 40 others worked to stop a fire from spreading beyond a dollar store in a Waterloo plaza Friday night. Police say it’s now being treated as a crime scene; a 14-year-old male has been arrested and charged with arson, endangering human life and possession of an incendiary device.

Flames were reported around 4 p.m. inside the Dollarama at Albert Street and Bearinger Road.

Lindsay Greatorex was working inside the store at the time.

“I saw a fire on our wall,” she told CTV News.

“It was from the floor to the ceiling.”

Greatorex said she grabbed a fire extinguisher, but it “didn’t really help” due to the size of the fire at that point.

As crowds gathered in the parking lot, the entire plaza was evacuated.

“I’m sure I’m taking smoke damage, at the very least. I’m hoping that’s all it is,” said Greg Watson of Water Depot.

As 6 p.m. approached, the smoke cloud grew in size and scope.

Waterloo Fire Rescue chief Richard Hepditch said that two firefighters were taken to hospital for precautionary reasons.

A "shelter in place" order was issued for people living near the fire scene.

Residents of Wildwood Place, Blythwood Road, Blythwood Place, Parkwood Court, Tamarack Drive, Smallwood Drive, Sorrel Place and portions of Hazel Street, Milford Avenue and Weber Street North were being asked to stay indoors with windows shut until further notice.

Firefighters were mounting a defensive attack on the fire, attempting to keep it contained to the Dollarama.

“Part of the roof has collapsed it’s pretty structurally unsafe. Until we can get a specialized piece of equipment here to remove portions of the roof we are sort of in abeyance right now,” Mike Ross, and investigator for the Ontario Fire Marshal said on Saturday.

The cause of the fire is not immediately clear, but officials consider this to be the biggest fire the city has seen in the last five years.

Firefighters believe it began in the back of the Dollarama.

There is no current estimate for damages, officials say it was a multi-million dollar fire.

The teen will be in court on Sunday.