NEW DELHI — A speeding school bus plunged off a mountainside in northern India on Monday, killing 23 children and four adults, an official said. Several children survived.

“The scene was full of panic, cries, chaos and disaster,” said Rakesh Pathania, a local politician who was at the site of the crash.

The bus, the authorities said, was carrying elementary school students from a private school in the state of Himachal Pradesh in the Himalayas when it swerved and fell hundreds of feet into a deep ravine around 3:15 p.m.