Hurricane Irma pounded Cuba's northern coast on Saturday as it headed for Florida, where millions of residents were told to evacuate after the storm killed 22 people in the Caribbean and left devastation in its wake.

Still a Category 5 storm when it crashed into Cuba in the early hours of Saturday, Irma weakened slightly as it tore along the island's northern coastline, downing power lines, bending palm trees and sending huge waves crashing over sea walls.

Maximum sustained winds dropped to around 130 miles per hour (215 km per hour) by 8 a.m. (1200 GMT) on Saturday, the U.S. National Hurricane Center (NHC) said, ranking it a dangerous Category 4 storm, the second-highest level.