Restoration experts are working through the night Sunday on the scene at Maywood's Proviso East High School Sunday afternoon, trying to repair as much of the damage from Saturday night's fire as possible so that classes can resume this week.
That won't happen before Wednesday however, as the school district's spokesperson said the school will be closed both Monday and Tuesday.
The fire, the cause of which is still under investigation, started around 9 Saturday night, while an end of year play was taking place inside the auditorium.
"Some of my friends were in the play and they said smoke was coming into the theatre room and they had to be evacuated out," said student Curtis Clark.
It took nearly an hour to extinguish the blaze. Maywood Fire Chief Craig Bronaugh says it appears to have started on the second floor.
The fire appears to have begun on the second floor. According to officials, there were about 30 people inside the building at the time.
"It extended to the third floor," he said. "They were able to contain it right where it was when they got here. At the time there was a play going out but people that were here were out when we got here."
Firefighters say everyone self-evacuated safely. It then took nearly an hour to extinguish the blaze, which at one point was elevated to a three-alarm fire.
While it will be a few days before the exact cause is determined, the fire chief in Maywood tells ABC7 Eyewitness News the fire was accidental. Investigators are not looking into foul play.