A 3-year-old boy was in hospital overnight after he fell three stories down the elevator shaft of a Toronto department store.

Emergency crews were called to the Bay store at the Eglinton Square shopping centre at around 7:45 p.m. The boy was with his mother who was shopping at the time.

The boy suffered minor injuries and was kept in hospital overnight for observation.

Police say they don't know how the boy ended up in the elevator shaft and are looking into whether the elevator was working at the time.

The Technical Safety and Standards Authority -- the group that regulates more than 43,000 elevators in Ontario -- is investigating the incident.

The store remained open throughout the evening and will also be open for business today.