At 1541 hours, Companies 10, 11 and 13 were dispatched to the above for a fire alarm. Crews inside found water leaking into the alarm panel. Engine 11-1 was due to the scene from its staging point for man power. As crews were investigating the cause of the water leak, there were some mandatory evacuations and also some sheltering in place. Some of our members assisted some of the elderly outside safely. It was later found that the water leaking was not from a broken sprinkler head. It was from a leaking HVAC unit. Systems were shut down and the residents were assisted back inside. We were available at 1701 hours.