The Office of the Fire Marshal has been notified after a large blaze burnt down part of a Baptist church in Burlington on Wednesday morning.

Fire crews were called to the Trinity Baptist Church, located on Appleby Line near Britannia Road, at around 1:15 a.m. after flames were spotted coming from the building.

“When we arrived on scene, the majority of the fire was on the exterior of the building, up the back wall into the eaves,” Burlington Fire Chief Charlie Birch told CP24 at the scene.

“They aggressively attacked the fire from the exterior.”

Fire crews from Hamilton and Milton also responded to the blaze.

Birch said that firefighters were not able get inside the building fast enough to attack the fire from the interior and a section of the building was gutted.

“The church is heavily damaged,” he said. “The roof has been burnt off.”

Birch said that while the old section of the church has been completely destroyed, crews managed to salvage the new part of the building.

“Structurally the walls are pretty good. Whether they can rebuild is yet to be determined,” he added.

The church's pastor Carl Muller told CTV News Toronto on Wednesday that he suspects arson is to blame for the fire. Muller said he believes the person who set the fire may have also been the one who spray painted the word “ISIS” on the side of the building.

“Some person who is malevolent (is at fault),” Muller said. “What his or her reason for writing is I really don’t know because I honestly don’t expect that particular organization to be active here targeting this particular church but I don’t know.”

Muller said the building holds many memories for parishioners and noted that it is "sad" to see the building destroyed.

"I was here at two o’clock in the morning watching the building burn and it broke my heart," he said.

Despite the incident, Muller said the congregation will move forward.

"The church is about people," he said.