A dozen people were hospitalized and up to 70 students impacted by the dislodging of a fire extinguisher in the hallway of a Virginia high school Tuesday. The extinguisher was accidentally knocked out of place by a student during a class change.

Video provided from inside Suffolk’s Nansemond River High shows the moment the hallway filled with gas and chemicals. The dozen injured include 11 students and one faculty member, who were sent to hospitals for treatment, according to reporting by local news channel WTKR.

Up to 70 students were complaining of respiratory problems following the incident, Suffolk Fire Chief Michael J. Barakey shared, but all but one student returned to class the next day, according to an update provided by Suffolk Public Schools.

"They all have been released from the hospital and all but one are present today at school. The parent of the absent student decided to keep that student home today," the update reads.

School notified parents in rotation

The one student who didn't return, Sionney Knight, told News 3 she thought the thick air was caused by something going wrong during a cooking class. “I thought they had burnt something, but when we go down there, it’s already everywhere," said Knight.

Knight's mother, Danielle Mosley, and other parents are still looking for more of an explanation. Parent, Teresa Walter, believes school officials waited too long to notify parents.

“By the time I got here, I knew that she was OK, but when I saw the pictures on my phone that she sent me, I was very upset,” Walter shared with News 3.

A school representative said faculty began notifying parents of students affected by the extinguisher as soon as the incident occurred and everyone else was notified later to prevent too much traffic coming in at once.

“Of course, they want to let the parents [of] kids that might have been injured or hurt know first out of respect, and I certainly understand that. But... she’s sending me pictures of this smoke-filled hallway and kids mass running through the hall. No, I don’t want to get that and then not hear from the school until two hours later,” said Walter.

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Suffolk Fire and Rescue, faculty comment on incident

The dry chemical powder released into the air from the incident is used to suppress class A, B and C fires, Suffolk fire officials said.

"These contain monoammonium phosphate, which comes out as a yellow powder," the National Capital Poison Center says. "The yellow color helps to distinguish it from other non-multipurpose extinguishers."

Reporters were provided with a copy of a letter sent to parents, in unity with school Principal Dr. Shawn Green's statement:

This morning during a class change, a fire extinguisher was mistakenly bumped into and subsequently fell from the wall to the floor and the extinguisher discharged. As a result, our school immediately moved to a Code Yellow emergency status to clear the hallways. The incident was contained swiftly, and there is no ongoing threat to the safety of our students or staff. Nine students were transported to the local hospital for further evaluation. Any student or staff or who complained of any discomfort were seen by emergency personnel on site.

I would like to express my gratitude to our dedicated staff and the emergency personnel who responded promptly and efficiently to this situation.