Aerial photos show patches of scorched earth in a west Ottawa wooded area damaged by fire, but it’s actually under the ground where the danger still lies.

A sprinkling of rain in Ottawa Sunday afternoon didn’t do much to help 30 to 35 firefighters battling hot spots in the forest off Moodie Drive in Nepean.

Ottawa fire platoon chief Jim Bloom said even with a water-bombing helicopter at their disposal, they still need that ground presence.

“What he does is he bombs the area and gets the fire knocked down, but he can't put it out,” he said. “What we have to do is we send people to the area on foot with axes and shovels and they actually have to dig.

“Because the fire is actually burning below ground, if we leave it the wind will pop up, it will start up and we'll be back in a forest fire situation.”

There are reports an improperly discarded cigarette could have caused the fire, with fire officials reminding people that a burn ban is in effect for parts of the city.

The fire started Thursday afternoon and has burnt more than 100 acres of brush and trees.

Officials said it could be as much as a week before the fire is out unless the area gets heavy rain.

With a report from CTV Ottawa’s Katie Griffin