The fire at 287 Commercial St. reached two alarms. All six people were treated for smoke inhalation.
Officials said the fire broke out in a first-floor hallway where a motorized wheelchair was plugged into an extension cord that was plugged into a second, smaller extension cord. It was then plugged into an ungrounded outlet.
May is Electrical Safety Month. In 2013, five people died in electrical home fires in Massachusetts; it was the second-leading cause of fire deaths behind smoking.