St. Hugo of the Hills Catholic School was evacuated Wednesday after close to a dozen children became sick during a school Mass.
One child passed out and four seventh-graders were taken to local hospitals. Doctors could not determine the cause of their headaches and nausea, but their conditions were not believed to be serious.
The other students and staff walked across the street to Oakland Community College where parents were directed to pick up their children.
Emergency medical crews and hazardous materials teams went to the school of 860 students and officials tried to determine what caused the illnesses.
Bloomfield Hills fire crews could not find any indication that carbon monoxide was the cause.