MILLIKEN, Colo. -- Investigators said a fire that burnt down a historic school house early Saturday morning was intentionally set.

The Milliken School House, which was nearly 100 years old, was burnt to the ground after it was spotted engulfed in flames at about 4:11 a.m.

“As soon as they left the station, they could see the size of the fire and called for more resources,” Milliken Fire Chief Ron Bateman said. Fire crews who first arrived at the scene had to immediately go into a defensive attack.

Also assisting the Milliken Fire Protection District were fire crews from Evans, Kersey and Johnstown.

The school house was built in 1917 and was used until 1948. Bateman said the structure had been abandoned for decades, and the fire department even used it for a training scenario a few years back.

Bateman said a $5,000 reward is being set up for tips that could lead to an arrest and conviction on who ignited the blaze. Anybody with information is asked to contact the arson tip line at 877-892-7766.