A Brooklyn school was locked down for nearly 2 1/2 hours after a teacher reported that a student had dropped a gun. No injuries were reported.

Department of Education spokeswoman Margie Feinberg says police were called to John Dewey High School after a teacher saw a student drop a gun in a classroom.

The student ran out of the classroom, and the lockdown was ordered around 12:30 p.m. The school was reopened shortly before 3 p.m.

The high school's Web site says it has about 3,100 students.

According to news reports, there have been at least two instances in the past two years where students had guns at the school, but no injuries were reported in those cases.