Washington Elementary School was evacuated for a short time Thursday morning after a gas odor was detected on the first floor, school officials said.
The call came in at 8:10 a.m., according to the county 911 center.
School district spokesman Patrick Gasper said the principal decided to evacuate.
Firefighters and Alliant Energy investigated with gas-detection meters and found no problems, said Battalion Chief Ryan Murphy of the Janesville Fire Department.
The outdoor temperature at the time of the evacuation was 37 degrees, according to the National Weather Service.
Murphy said the evacuation came as students were still arriving at school, lasted 10 to 15 minutes, and staff did a good job keeping students organized.
Murphy said firefighters would continue to investigate to verify their findings.
Murphy said the police department was asked to issue a Nixle social-media alert to allay any fears because of Wednesday’s school shooting in Florida.