More than 4,000 students headed back to John F. Kennedy high school in Marble Hill on Wednesday, less than one month after part of the school was torn apart by an explosion.
Parts of the school are still closed as repairs continue to be made, but last week the Department of Education deemed it safe enough to open for the first day of classes.
Investigators say the blast on August 20 was caused by a construction worker who lit a match to test a newly installed gas line inside one of the labs on the sixth floor.
The explosion left a gaping hole in the building, which houses eight schools.
Three workers were seriously burned.
Students who spoke with NY1 say they didn't think they would be back to school so quickly.
"I was shocked, I really didn't expect that to happen," said one student.
"I was just surprised and at first I thought I didn't think we were gonna have school for the first day," said another student.
Mayor Bill de Blasio is scheduled to visit the campus Wednesday to meet with students and faculty, as well as the workers who have been making repairs to the building.