This would never have happened at a certain broadcaster I used to work for.
The generator was in its own separate building, and tested twice a year. Unfortunately, after 20 odd years of testing, the test failed. There was a book with all engineers responsibilities, their deputies, their managers, all the phone numbers etc. The book contained every procedure, every workaround, every aspect of how to get back to broadcasting within 3 minutes in the event of a supply failure. Except there was one little omission - there was no schedule nor person responsible to ensure that the diesel tank was checked and refilled. The test failed not because of a fire but because of the lack of fire inside each of its cylinders, because there was no fuel.
Still, that is what tests are for - to find that one thing that no one had thought of before.