Firefighters say a forklift hit part of the sprinkler system at the Nandino Blvd. post office, causing thousands of gallons of water into the building.
Officials evacuated workers shortly after the accident around 4:00 a.m. Monday.
Officials were concerned over the possibility of workers slipping or falling and the fire hazard.
Firefighters and maintenance crews soon responded and gave the building the all clear.
Work is now back to normal.
Officials say no mail was damaged. However, some mail may be delayed.