London fire crews tackling large barn, grass fire in southeast London, Ont.

RAW: London fire tackle stubborn barn blaze CTV London's videographer Jim Knight was on scene of a large barn and brush fire near Highway 401 Tuesday afternoon.

London fire crews are currently tackling a "large grass fire and working barn fire" in the southeast section of the city Tuesday afternoon and are asking the public to avoid the area.

According to a tweet from the London Fire Department (LFD), crews were dispatched to the area of Old Victoria Road and Wilton Grove Road, located near Highway 401, due to multiple 9-1-1 calls of a large blaze at a barn.

Upon arrival, large flames and heavy plumes of smoke could be seen.

Fire crews said they are “attacking the fire defensively," as the roof was collapsing in on itself.

According to London fire, a number of factors are contributing to the size of the blaze.

"A lot of hay in that area, so I think at this time there's no animals in this barn. It's a lot of hay, so that's a lot of combustibles in there that have sparked such a large fire in that barn so quickly," explained LFD Platoon Chief Kirk Loveland. "Now all the other areas around it are being protected. We've had a couple of things breached but they're not a flammable product so there is no concern as far as hazardous material goes at this time."

In the meantime, the London Police Service is asking the public to avoid the area of Old Victoria Road between Wilton Grove Road and Discovery Drive, which is currently closed.

As of early Tuesday evening, fire crews were in the process of protecting other buildings on site, including one containing cattle.

By Tuesday evening London fire said in an update that they remain on scene and that two backhoes are pulling the fire scene apart. They said they'll continue to be on scene for some time to come due to spot fires "that continue to burn."

No injuries have been reported.

The cause of the blaze and estimated cost of damages currently remains unknown.

"Our thanks to [Central Elgin Fire Rescue] and Thames Centre Fire for mutual aid assistance," London fire wrote on Twitter.

This is a developing story 

— With files from CTV News London's Jim Knight