Ottawa police say pepper spray may have been the cause of an evacuation that forced dozens of people out of their homes in the city's west end.

About 30 units were evacuated at an apartment building at 1411 Morisset Ave. at about 8:30 p.m. Wednesday after 9-1-1 was flooded with calls from tenants regarding a strange smell in the building.

Paramedics took two residents to hospital; 10 others were treated for eye and nose irritation.

About 30 firefighters were also called in to help ventilate the building.

Witnesses apparently told police they spotted some young men horsing around with pepper spray that night. However, the illegal spray was not found.