Police officers raced to the school. Some students trembled as they crouched in corners trying to hide. A few staff members began to pray.
"We really thought we were not going home that night," one teacher said. "It was probably the worst feeling I ever had in my life."
Less than a week after the massacre at Sandy Hook Elementary School, in Newtown, Conn., a lockdown exercise on Tuesday morning at Public School 79 in East Harlem caused alarm, as not everyone understood there was to be a drill.
On Wednesday, Marge Feinberg, a spokeswoman for the New York City Education Department, said only, "We are looking into how this drill was conducted." The school's principal, Greer Phillips, declined to comment.
P.S. 79, the Horan School, serves 300 students with special needs, including those with severe emotional disabilities, autism, cerebral palsy and other disorders. The students range in age from 12 to 21, one staff member said.
The lockdown drill began about 10 a.m. on Tuesday with a woman's voice on the school's loudspeaker saying, " 'Shooter,' or 'intruder,' and 'get out, get out, lockdown,' " said the staff member, who added that it seemed so realistic that it was hard to tell if the woman speaking was actually talking to a gunman or to teachers and students throughout the school.
At 10:01 a.m., a woman dialed 911 from her cellphone and said she had heard a message over the loudspeaker "that there was an intruder in the school, and that she was in the class with her students," said a Police Department spokeswoman.
Officers from the 25th Precinct station house responded, she said. When they arrived a minute later, school officials told them that it was just a drill.
Santos Sabio, a teacher at the school, said she had panicked at first but realized within five minutes that the exercise was a drill. "It was a surprise, but it shouldn't be a surprise," she said.
This article originally appeared in The New York Times.