The School Without Walls was evacuated Thursday after it received a suspicious envelope in the mail containing an unidentified white powder.

Principal Richard Trogisch contacted the police after opening the envelope and finding “al-Qaida” written on a note in addition to the white substance.

“I think it’s a reaction to Osama bin Laden’s capture,” Trogisch said. “Somebody’s taking advantage of this to get some press.”

Trogisch said the envelope was mailed from North Dallas, Tex. and that more than 10 other schools in the area received similar packages. School Without Walls is located on G Street between 21st and 22nd streets.

Officials tested the powder from one of the envelopes sent to a different school and confirmed it to be cornstarch, according to NBC.

Students were informed when school officials announced over the PA system that a class-wide lockdown was put in effect, senior Giovanni Chiappano said.

Trogisch then made a second announcement confirming the suspicious envelope and evacuating the whole school to Kogan Plaza.

“Once the principal came back up… people kind of calmed down a bit,” junior David Hine said. “But people were definitely a little bit scared.”

A Metropolitan Police Department officer declined to comment.