A sprinkler system extinguished a fire on the third floor Kinau Street apartment building early today, leaving arriving firefighters with only the job of mopping up the water.

The fire department received two alarm calls at 1:30 a.m. involving an activated fire alarm and odor of smoke coming from an apartment building in the 1100 block of Kinau Street.

By time firefighters arrived six minutes later, the fire had been extinguished by a sprinkler system.

There was no immediate estimate of damage and fire investigators are still trying to determine cause of the fire. No other units in the building reported damage. No injuries were reported.