Plumbing and maintenance
The first ten minutes of a burst pipe
The order matters: stop the water, kill the risk, then limit damage. Everything else can wait until those three are done.
The practical points
Close the internal stopcock, then open the lowest cold taps to drain the system and reduce pressure at the split.
Where water is near lighting or sockets, isolate the affected electrical circuit before dealing with the water.
Your questions answered
Should I catch the water or find the leak?
Stop the supply first, containers are a distant second priority.
When should I call?
As soon as the supply is off. Describe where the water is showing and which room is above it.
Getting burst pipe response right first time
Describe what is there now and what is bothering you. It is usually clear within a message or two whether this is straightforward or needs a look.