More than 100 cows are believed to have been lost in a barn fire Monday morning at a dairy farm near Truro, N.S.

Eight fire departments responded the fire at Green Oaks Dairy Farm in Green Oaks, N.S.

Cobequid District Fire Brigade Deputy Chief Tyler Ash said firefighters received a report of a fully involved fire at about 9:15 a.m.

“We have no idea what could cause this at this time. It's currently under investigation,” Ash said.

Trucks hauled water from the nearby Shubenacadie River to help fight the fire, while three county-run fire departments were called in to cover for the many firefighters kept busy by the barn fire.

“We did call in an excavator to pull away some steel. It was a steel-clad burn, so it was brought in basically to gain access to the fire,” Ash said.

Joe Stokdijk, a young man who works at the dairy farm, says he had the morning off but other workers left around 7:30 a.m., and he believes the fire started shortly after that.

“A lot of good cows were lost … probably a little more than 120,” Stokdijk said.

The farm is owned by Phillip Burris, and a sign out front indicates it’s been operating as a family farm since 1785.

Information from the Nova Scotia Federation of Agriculture says Burris has 300 cows in his dairy cow herd, milks 140 of them and grows forage and corn.

With files from CTV Atlantic’s Jacqueline Foster