MIAMI — Hurricane Jose became an “extremely dangerous” Category 4 hurricane Friday, threatening Caribbean islands already devastated by Hurricane Irma, the U.S. National Hurricane Center said.

As of Friday afternoon, Hurricane Jose had maximum sustained winds of 150 mph as it moved west-northwest toward the northern Leeward Islands at a speedy 18 mph.

The eye of the storm was located about 380 miles east-southeast from the islands. It was expected to pass near or east of the northeastern Leeward Islands on Saturday.

“I don’t think it takes a rocket scientist to know that further damage is imminent,” said Inspector Frankie Thomas of the Royal Police Force of Antigua and Barbuda.

Hurricane Irma weakened from a Category 5 to a still-fearsome Category 4 on Friday morning with winds of 155 mph.

The hurricane smashed homes, schools, stores, roads and boats on Wednesday and Thursday as it rolled over some of the world’s most famous beach paradises, including St. Martin, St. Barts, St. Thomas, Barbuda and Anguilla.

It knocked out power, water and telephone service, trapped thousands of tourists, and stripped the trees of leaves, leaving an eerie, blasted-looking landscape. Authorities reported looting and gunfire in St. Martin, and a curfew was imposed in the U.S. Virgin Islands.

On the island of St. Thomas, part of the U.S. Virgin Islands, power lines and towers were toppled, leaves were stripped off plants and trees, a water and sewage treatment plant was heavily damaged, and the harbor was in ruins, along with hundreds of homes and dozens of businesses.

Thousands of tourists were trapped on St. Martin, St. Barts, and the Virgin Islands in the path of Hurricane Jose. Authorities rushed to evacuate as many people as possible from Barbuda ahead of the new storm.

Some of the Irma-ravaged islands could see tropical-storm force winds and heavy rain from Hurricane Jose, said Jeff Masters of the private forecasting service Weather Underground.

“It’s insult added to injury definitely, but nothing compared to what they already went through,” Masters said. “It’s going to hamper relief efforts, so that’s a big deal.”

On St. Martin, which is divided between Dutch and French control, cafes and shops were swamped, and the storm left gnarled black branches stripped of leaves. Battered cars, corrugated metal, plywood, wrought iron and other debris covered street after street. Roofs were torn off numerous houses.

There was little left of the Hotel Mercure but its sign, painted on a still-standing wall.

The cleanup was already underway for some. One man chopped at the branches of a bare tree. Another heaved what appeared to be furniture stuffing onto a pile. People sat in chairs outside a hospital, waiting to be seen.

“We’ve had quite some looting that has taken place, unfortunately,” said William Marlin, prime minister of the Dutch side of the island.

Marlin said that in the aftermath of such a disaster, “people become kind of hopeless and there is no communication.”

The hospital on St. Thomas was destroyed and dozens of patients were being evacuated to St. Croix and Puerto Rico by the U.S. Coast Guard.

Gov. Kenneth Mapp of the U.S. Virgin Islands imposed a 6 p.m. curfew. The primary focus for now is “making sure people have meals, water and shelter,” Mapp said. “An event of this magnitude is very chilling.”