Fateful moments of Bhopal gas disaster

In the apocalyptic moments on the cold wintry night of December 2-3,1984, people simply started dying in the most hideous ways after a toxic gas leak. 

Some vomited uncontrollably, went into convulsions and fell dead.

Others choked to death, drowning in their own body fluids after the Union Carbide's pesticide factory whose safety systems were reportedly not functioning exploded in Bhopal filling the streets of the city with toxic clouds of methyl isocyanate gas.

During the intervening night December 2, a large amount of water entered 'tank 610' which contained 42 tonnes MIC, much more than safety rules permitted.

A runaway reaction started, which was accelerated by contaminants, high temperatures and other factors. The reaction generated a major increase in the temperature inside the tank to over 200' C. This forced the emergency venting of pressure from the MIC holding tank, releasing a large volume of toxic gases.

The reaction was speeded up by the presence of iron from corroding non-stainless steel pipelines. It is known that workers cleaned pipelines with water but they were not told by the supervisor to add a slip-blind water isolation plate. Because of this, and of the bad maintenance, the workers consider it possible for water to have accidentally entered the MIC tank.

Union Carbide first maintained that a "disgruntled worker" deliberately connected a hose to a pressure gauge.

UCC's investigation team found no evidence of the suggested
connection.

The timeline of the fateful intervening night of December 2-3 as per available information.

The scene inside
21.00 Water cleaning of pipes starts.
22.00 Water enters tank 610, reaction starts.
22.30 Gases are emitted from the vent gas scrubber tower.
00.30 The large siren sounds and is turned off.
00.50 The siren is heard within the plant area. The workers  escape.

The scene outside
22.30 First sensations due to the gases are felt—-suffocation, cough, burning eyes and vomiting. 
1.00 Police are alerted. Residents of the area evacuate. Union Carbide director denies any leak.
2.00 The first people reached Hamidia hospital. Symptoms include visual impairment and blindness, respiratory difficulties, frothing at the mouth, and vomitting.
2.10 The alarm is heard outside the plant. 
4.00 The gases are brought under control. 
6.00 A police loudspeaker broadcasts: "Everything is normal".