What to do first
If water is actively spreading, turn the AC off at the thermostat and move anything that could be damaged. Do not keep running the system just to see if it clears itself. Take a photo of where the water is showing up, then note whether the indoor blower is still running.
Why the AC may have shut itself off
Many systems have a float switch or safety switch that stops cooling when the drain backs up. That shutoff is meant to protect the home from water damage. If the thermostat is calling but the system will not run and water is nearby, include that detail in the text.
When water points to a bigger cooling issue
A leaking AC is not always only a drain-line problem. Ice on the coil can melt into water after the system is turned off, and that may point back to airflow, coil condition, refrigerant-side concerns, or another diagnostic issue. The $95 Springfield Diagnostic gives Scott a clean starting point when the cause is not obvious.
Read the drain line service page