Method for extinguishing a fire in a space, especially in a tunnel or equivalent, in which method an extinguishing medium is sprayed in the space by means of spraying heads. In a first stage of the method, the flow and temperature of the hot gases produced by the fire are influenced by spraying an extinguishing medium into the space, especially by creating in the space at least one curtain (7) of extinguishing medium, and at least some spraying heads (11, 12) in the space are pre-activated into a state of readiness, and in a second stage at least one spraying head is activated to produce a spray of extinguishing medium. The invention also concerns an apparatus.