The hooter was sounded at 4 pm and 4199 employees present in the building were evacuated in 12 minutes, Mantralaya sources said.
The Brihanmumbai Municipal Corporation (BMC) control room, however, could be alerted about the fire only at 4:07 PM, a delay of seven minutes.
"The delay of seven minutes was because the Mantralaya control room has been shifted to Barrack number eight which is about 1.5 km away from Mantralaya building. Evacuation was the main focus this time. The fire engine and an ambulance arrived in eight minutes from the time of the call at 4:15 PM," sources added.
Since the lifts were already brought down to the ground floor, the staff from each of the floor was taken to safety from different exit routes.
Each floor had a floor marshal who was assisted by a deputy floor marshal and an assistant floor marshal.
"They had a list of employees of each of the floors and after the staff was brought down, a head count was taken to check if anybody was left behind," sources added.
More From This Section
Map of the building including the position of the exit routes was displayed in each floor.
The Home guards and personnel from the fire service, Mantralaya security and Mumbai police among others participated in the exercise, sources said. (MORE)