At 10.30 am on Wednesday, the Himachal Pradesh capital was roused to action as hooters blared, announcing an earthquake. Residents scurried even though the quake could not quite be felt.
It was only later that authorities let on that a mock drill was conducted, to check preparedness of emergency services, including police and the fire service, if disaster struck.
The National Disaster Management Authority's (NDMA) B.K. Khanna said the drill was held to also know the reaction time of residents in case a quake of more than eight on the Richter scale struck Shimla.
The hill state falls in zones IV and V, with severe seismic sensitivity.
"As per studies by IITs, if an earthquake measuring eight on the Richter scale hits the state with its epicentre in Sundernagar at night, 1.6 lakh people will die and over 11 lakh will be injured," Khanna said.
Himachal Pradesh is home to over 68 lakh people.
NDMA officials said the state's widening concrete jungle, which has come up without conforming to safety standards prescribed to withstand quakes, could exacerbate loss of life and damage to property.
Bigger towns like Shimla, Solan, Kangra, Dharamsala and Mandi have large tracts of land given over to unplanned construction.
Shimla falls in seismic zone IV. Officials said not even two percent of its buildings can withstand earthquakes of high intensity.
Officials say Shimla's northern slope of the historic Ridge, an open space above the Mall, extending to the Grand Hotel in the west and Lakkar Bazaar in the east, is sinking.
Shimla has 187 buildings with more than five floors.
Planned for a maximum population of 16,000, Shimla now supports 236,000 people, as per census figures for 2011.
Himachal Pradesh witnessed its most devastating earthquake in 1905 in the Kangra Valley which left more than 20,000 people dead.