The first job is protecting what's inside. Move furniture and electronics away from the drip, put down a bucket or towels, and if the ceiling is bulging with water, poke a small hole at the lowest point so it drains into the bucket instead of bringing the drywall down.
Don't go up on the roof yourself, especially while it's wet or windy. Wet shingles are slick, and a leak is rarely directly above the spot where water shows up inside. Water runs along the decking and rafters before it finds a way down.
Take photos of the ceiling, walls, and anything that got wet. Then call a roofer. ZZ TEST Bright Roofing 10240007 is at (214) 555-0142 for active leaks across Dallas, Plano, and Irving, and we offer a free roof inspection to find the source.
When we arrive, we trace the leak back to its source, most often chimney flashing, a valley, or a cracked pipe boot. If the weather allows, we repair it right away. If it doesn't, we protect the area until a permanent repair can be made, then come back and fix it properly.