Residents of a Saskatoon apartment building were forced from their homes Friday morning after a high level of carbon monoxide was fund in the building.

Saskatoon firefighters were called just before 7 a.m. after a CO detector began sounding in the building located on Eighth Street near Broadway Avenue.

Fire crews tested the interior air quality and a high CO reading of 138 ppm found in the apartment’s service room.

The 30-unit apartment building was evacuated and Saskatoon Transit provided a city bus to shelter the building’s occupants.

SaskEnergy responded to the building where a covered cold air intake was found to be preventing the building’s heating unit from functioning properly.

The CO level in the building dropped immediately once the intake was uncovered, and residents were allowed back into the building.