A massive tornado that tore through the southwest Missouri city of Joplin killed at least 89 people, but authorities warned that the death toll could climb Monday as search and rescuers continued their work at sunrise.

City manager Mark Rohr announced the number of known dead at a pre-dawn news conference outside the wreckage of a hospital that took a direct hit from Sunday's storm. Rohr said the twister cut a path nearly six miles long and more than a half-mile wide through the center of town, adding that tornado sirens gave residents about a 20-minute warning before the tornado touched down on the city's west side.