TREASURE ISLAND, Fla. — Hurricane Milton explosively intensified Monday into one of the strongest hurricanes on record as it hurtled toward a highly populated stretch of Florida’s coast, where residents are still recovering from another powerful storm less than two weeks ago.

Counties that line the Gulf Coast ordered people to leave in what is expected to be the largest evacuation in the state since at least Hurricane Irma in 2017. By the afternoon, highways were beginning to clog and long lines had formed at gas stations.