LEWISTON — About 100 workers and bowlers had to evacuate a building on Mollison Way in Lewiston Tuesday morning because of carbon monoxide in the building.

The incident was reported at 9:30 a.m. and was caused by a snow drift covering an exhaust vent on a heating unit.

Workers and two bowling leagues – the Morning Glories and Young at Heart – had to leave the building until the fire department could vent the fumes.

The building houses Sparetime Bowling, Carbonite database services and Merrimack River Medical Services.

People were allowed to return to the building by 11:30 a.m.