Not long after the incident, which occurred Thursday morning during singing rehearsals at Aspenwood elementary, the school's principal called in emergency officials, said Cheryl Quinton, a spokeswoman with the Coquitlam school district.
"The principal called the paramedics, and they recommended that as a precaution — they didn't see anything overtly evident — but just as a precaution take them to hospital and get them checked out."
Initially, Quinton said two students were taken to hospital, but Remo Faedo, Port Moody's fire chief, said at least six were taken to hospital.
Faedo said one of the children passed out, was injured and started bleeding.
Faedo said after arriving on scene, fire officials activated the fire alarm and evacuated the school because other students were complaining of flu-like symptoms and there was potential that there could be an atmospheric problem in the school.
He said firefighters determined there wasn't a problem, so they brought the students back into the gymnasium but also conducted more tests.
Faedo said firefighters test for possible problems like natural gas, low-oxygen levels and carbon monoxide.
"We came up with nothing," he said.
Quinton said the school released the students early for the day.
Faedo said the fire department has given the school the all clear to open for Friday.
The Coquitlam School District has 45 elementary, 13 middle and nine secondary schools, serving about 30,000 students in Belcarra, Ioco, Anmore, Port Moody, Coquitlam and Port Coquitlam.
--by Keven Drews in Vancouver