When the first firefighters reached reactor unit 4 of the Chernobyl nuclear power plant on the night of April 26, 1986, the roof was on fire. Debris lay on the site and parts of the building were torn open. At the time, no one knew exactly what had happened. The men immediately began extinguishing the fire, climbed onto the roof and moved materials aside. The first radiation measurements did not provide a clear picture: the measuring devices reached their limits. There was no protection against radiation, and there were no warnings to the emergency services on site or even to the surrounding population.
