In September of 2008 there were two fires in Las Vegas casinos less than 12 hours apart. The fire sprinklers prevented a potential catastrophe in both cases.
On September 23rd at around 6:00 AM there was a fire in a guest room at the Bellagio Resort. The sprinkler system activated and extinguished the fire. No one was seriously injured.
On the evening of the same day there was a fire in a Mechanical Room at the Venetian Resort. Again, the sprinkler system activated and extinguished the fire. No one was injured and there was no need to evacuate the resort.
These two incidents, which essentially went unreported in the news, are in clear contrast to the fire at the MGM in 1980 when 87 people died and more than 600 were injured.
There were no sprinklers in the MGM at the time.