In case of an emergency situation you have to find as much information as possible to eliminate it. There are couple of intervention points of an irrigation system to do it.
First point is the first main isolator valve. In case of a continuous leak it’s recommended to turn off.
Also advised to switch the electric isolator of the controller off to prevent the system running. In lack of this switch, turn the dial of controller to off if it exists. There are different methods to do it on battery controllers, please refer to the User manual.
In case of a boosted system switching off the power supply of pump is also advised. Usually the emergency switch is nearby the pump at an accessible place for emergency purposes. It can be a socket switch, fuse box, circuit breaker, rotating switch, etc.
If you don’t find it, try to follow the cables start from the pump (possibly come up from the tank) till you find the isolator switch.