BOISE — A fast-moving grass fire set 50 acres ablaze in the Boise foothills Sunday afternoon, threatening a couple homes.

Plumes of smoke were visible throughout much of the city.

The Boise Fire Department says crews first responded to a small fire, burning less than an acre, off Sunset Peak Road just before 3 p.m.

Then twenty minutes later, crews were diverted to a second, much larger fire, burning off the 5000 block of Bogus Basin Road, near the intersection with West Baker Ridge Lane.

As of 7 p.m. Sunday the fire was 50 percent contained.

Fire officials say two homes were threatened, and one them was saved thanks to defensible space.

“One of the homes did have some defensible space around it and it burned the vegetation up to their defensible space and basically went out,” said Tony Piscopo, a division chief with BFD. “It was a big success for those homeowners they didn’t have any damage to their property at all.”

Piscopo says crews were able to spare the second home using a bulldozer to create space between the house and the fire.

In the end, no structures were damaged and no one was injured.

75 fire personnel from Boise Fire, the Bureau of Land Management, the Forest Service, and Boise Police responded.

Crews will continue to mop up and monitor the fire near Bogus Basin Road throughout Sunday night.

An investigation is underway into the cause of both fires, which officials called "suspicious" because of how close together in time and proximity they were.