Short answer
Turn the AC off to stop more water, put a bucket under the drip, and check the secondary drain pan. Most ceiling leaks under an attic air handler come from a clogged condensate drain, a cracked pan or a missing float switch.
Right now
Turn the system off at the thermostat. If the ceiling is sagging, poke a small hole in the lowest point over a bucket to drain it in a controlled way, and keep people away.
Why it happens
The AC removes a lot of water on humid monsoon days. Algae and scale clog the drain trap, the primary pan overflows, and a rusted or missing secondary pan lets it through.
The fix
A tech clears and flushes the line, checks the trap and pan, and installs or tests a float switch so it shuts off before overflowing next time. Drywall repair is a separate trade.
Questions
Will homeowners insurance cover AC water damage?+
Policies vary. Sudden water damage is sometimes covered while slow leaks or maintenance issues usually aren't. Take photos and check with your insurer.
Editorial note: this guide is general information for homeowners, not a diagnosis. Desertline Heating & Air is a referral service; a licensed contractor should inspect your equipment before repairs.