A fire broke out at Chicago Academy High School in Chicago's Dunning neighborhood early Thursday morning. 

Just after 1 a.m., the Chicago Police Department said firefighters responded to a fire on the third floor of the school, in the 3400 block of North Austin Avenue.

Police confirmed no one was inside the school at the time of the fire. 

Chicago Academy officials confirmed students were moved to Thorp Scholastic Academy for the day and would return for dismissal. School officials said they did not hold regularly scheduled classes. 

Video from the scene shows heavy smoke and flames pouring out of the roof of the school. Dozens of firefighters battled the fire overnight. 

Neighbors told CBS News Chicago that overnight construction on the school had been underway for the last month. 

One of the neighbors said he heard a sound around 1:30 a.m. but did not know what caused it. 

The extent of the damage is unknown at this time. 

Chicago fire officials are investigating the cause of the fire. 

This is a developing story. CBS News Chicago will continue to provide updates.