Students at middle school in Oakville section of Watertown were dismissed early on Thursday after several got sick.
The Watertown superintendent's office said that some children got sick at Swift Middle School located on Colonial Street.
After students were evacuated, 35 students were taken by ambulance to a local hospital for unexplained illness, officials said.
A majority of the students were taken to Waterbury Hospital while the rest were transported to St. Mary’s Hospital. Police said the students’ injuries are non-life-threatening.
The students told the administration that they experienced symptoms of light-headedness, nauseous and dizziness.
"I had a small headache right before the chaos kind of started," said sixth grader Evan Davidson. "They were showing dizziness, headaches, stomach aches...a few of my friends were loaded onto ambulances and taken to the hospital."
One student lost consciousness, but officials stressed that they don't know if this was connected to the other students.
The Watertown Fire Department said firefighters were called to the school for a report of a mysterious odor.
Crews with gas readers were called to scene. However, nothing was located by them.
"It can test for five different gases and there were no readings of any consequence on any meters," said Watertown Fire Chief Larry Black.
Students all around the school experienced the illness and it was not contained to one area of the building.
A faint electrical burning smell was later discovered in the gym. However, the administration said it is unclear if it is related to this incident.
Officials told Eyewitness News that students were sent early for the day.
On Thursday evening, officials from the Department of Energy and Environmental Protection completed a sweep of the school, and nothing out of the ordinary was found.
School is expected to be open on Friday and fire officials said they will go through the school looking for gas readings at 6 a.m. just to be sure.
Parents were alerted through text messages and many were seen taking their students home.
"They all seemed fine, more tears than anything at this point," said parent Sherri Iava.
Parents will be notified if school is canceled on Friday.
Copyright 2015 WFSB (Meredith Corporation). All rights reserved.