A lab at McMaster University in Hamilton that was evacuated due to a possible gas leak reopened Tuesday afternoon.

A researcher in a lab in the Tandem Accelerator Building was purging a tank with nitrogen when an alarm sounded.

The Tandem Accelerator Building and the General Sciences Building were both evacuated.

Hamilton police say they got a call at about 1:20 p.m. from the McMaster Communications Centre. Fire crews also responded.

Traffic is now being allowed into the campus after being kept out earlier this afternoon.

No one was injured in the incident.

With files from The Canadian Press