What to do in the event of fire at workplace?

There should be a comprehensive fire action plan and regular fire drills for dealing with such situation in your organisation. Here's what need to do in event of fire:

Raise the alarm 
A person discovering fire should raise alarm manually if possible. The alarm can be electric or manually operated system such as bells or rotary gong etc. Fire alarm usually operates automatically by breaking the glass in front of fire alarm switch. Alarm should be clearly audible throughout the building.

Alert the staff and summon fire brigade
Need to alert the the staff so that the persons who are required to assist in situation resume their roles and ensure evacuation of people especially those who need assistance. While summon the fire brigade and direct emergency services.

Fight the fire and prevent it from spreading
Fight the fire using fire fighting equipment such as fire hose, Fire extinguishers, fire blankets. but one must not endanger himself while trying to fight the large or spreading fire.

Evacuate the building
Ensure that everyone has left the building or is leaving. An up-to scale, single line drawing of premises should be present. Their should be adequate emergency escape routes with fire doors. It should be well lit and free of any obstruction and clear directional signs showing where to go. Everyone need to be evacuated by help of fire warden or fire marshals and be collected at assembly point or muster point where roll calls would be carried out to ensure complete evacuation.