A frozen pipe can split even before you see a leak. Shut off the water if you suspect a rupture, open the affected faucet, and thaw only accessible sections slowly without an open flame.
Look for signs of a split first
Bulges, cracks, water on walls or floors, and a pressure drop after thawing can indicate a leak. If you see them, shut off the main water supply before continuing.
Open the affected faucet
Leave the corresponding hot or cold faucet open. As the pipe warms, water and pressure need an outlet, and returning flow helps show when thawing begins.
Apply gentle heat from the faucet side
Use warm air, hot towels, or a heating pad intended for that use. Work gradually from the faucet side toward the frozen section so meltwater has a path out.
Never use a torch or open flame
Flame can damage pipe, ignite hidden materials, and start a fire inside a wall. If the frozen section is inaccessible or you cannot locate it, call a plumber.