Water Coming In Now
While water is coming in, the job is to control it and protect the house. The roof gets dealt with when somebody can safely be on it.
Short answer
Contain the water, move what is below it, and relieve the pressure by making a small hole in a bulging ceiling so it drains in one place rather than collapsing. Turn off the electrical circuit if water is near a fixture. Do not go on the roof in the dark, in wind or in ice.
In the first ten minutes
Move furniture, electronics and anything of value out from under it, and get something absorbent down.
Put a bucket under the drip and something to break the splash.
If the ceiling is bulging, make a small hole at the lowest point of the bulge and let it drain into a container. A controlled hole is far better than a collapsed ceiling.
If water is near a light fixture, a pot light or an outlet, switch that circuit off at the panel.
Go into the attic if you safely can and put a container under the drip up there instead, which stops it reaching the ceiling at all.
And photograph everything, because the insurance claim starts now.
Do not go on the roof
Not in the dark, not in wind, not in rain, and absolutely not in ice or snow. More people are hurt dealing with a roof leak than by the leak. A leak overnight is a containment problem until morning, and containment can be done from inside.
What an emergency call can do
Tarp the affected area, which is the usual emergency measure and is weather and daylight dependent.
A temporary patch on an accessible flashing or penetration.
Clear an ice dam or a blocked drain where that is the cause.
Identify the source so the permanent repair is scoped properly.
Document the condition for the insurance claim.
And tell you honestly whether it can be worked on tonight or whether containment until the morning is the right answer, which it frequently is.
The insurance side
Notify the insurer promptly, which most policies require.
Emergency measures to prevent further damage are normally covered, and most policies also oblige you to take them.
Keep the emergency invoice separate from the permanent repair.
Photograph before, during and after, including the ceiling, the contents and the attic.
Understand that the policy will generally cover the resulting damage and may not cover the roof repair itself where the cause is wear and age — which is a distinction worth knowing before the adjuster raises it.
And keep the damaged contents until the claim is settled rather than disposing of them.
Common questions
Should I make a hole in a bulging ceiling?
Yes, a small one at the lowest point. A controlled drain beats a collapse.
Can somebody tarp it tonight?
Sometimes. Not in wind, ice or darkness. Containment from inside is the overnight answer.
Does insurance cover it?
Emergency measures and resulting damage usually. The roof repair itself may not where the cause is wear.