KEY WEST, Fla. — Hurricane Irma barreled toward the U.S. mainland Wednesday, prompting the southernmost county in Florida to begin evacuations along its lone island-hopping highway while the “potentially catastrophic Category 5″ storm menaced Puerto Rico and a wide swath of the Caribbean.
Forecasters said Irma posed an increasing threat to South Florida, a sprawling and densely populated mass of cities and suburbs hugging the coastline. As dire warnings mounted, schools and offices began to shut down, grocery store shelves were wiped clean and authorities ordered evacuations with more to follow.
