SACO — Firefighters battling a blaze at an auto body shop in Saco knew when they arrived Monday around noon that one of the four buildings on the property was too far gone, so they concentrated on saving the other three structures.

Crews from Saco and surrounding communities stayed outside the burning structure at R.P. Bell Collision on Burrows Street, using hoses from the ground and from a telescoping arm of a bucket truck to spray water to contain the flames to the building dedicated to painting cars.

“We were concerned about building collapse right from the beginning, and at this point that has happened,” Saco Fire Chief John Duross said shortly after 1 p.m. when the roof of the building collapsed and the fire was out but continued to smoke.

Using what Duross called a “defensive attack,” they allowed the 3,000-square-foot auto painting building to burn and saved the other detached buildings on the property, located near the intersection of Route 1 and Ocean Park Road.

Two workers were inside the painting building when the fire starated and they called 911 after escaping the building around 11:48 a.m. A total of about 10 employees working on the property in the various buildings evacuated. No employees or firefighters were hurt.

The company’s owner, Phil O’Connor, said he was called after the fire started and spoke to authorities after learning that his employees were safe.

“Nobody knows what happened. It happened so quickly. Everyone got out,” said O’Connor, who has owned the company for the last seven years.

O’Connor said that though the painting facility had room for up to seven vehicles, only two were inside. Both cars were destroyed, and he was preparing to inform the owners.

O’Connor said R.P. Bell Collision is owned by a larger company, POC Collision, which also has auto businesses in Lewiston and Auburn. Workers will be able to resume repairs in the remaining three buildings in Saco once the fire is out and transfer other work to the Lewiston and Auburn locations to keep repairs on schedule.

The fire chief, who spoke as firefighters continued to spray the collapsed building, said investigators still do not know what caused the blaze.

“At this time, the fire is still under investigation by the State Fire Marshal’s Office,” Duross said.