The vault in the 1300 block of North Lake Shore Drive caught fire about 2 p.m., Fire Media Affairs chief Larry Langford said.
He said at least two buildings on that block lost power because of the fire.
Firefighters were waiting for ComEd officials to arrive on the scene, Langford said.
Langford confirmed people were stuck in elevators from the buildings that lost power but did not know how many. Firefighters were working to get them out as of 2:15 p.m., he said.
No one was injured in the incident.
(Source: Sun-Times Media Wire - Copyright Chicago Sun-Times 2014.)