Typhoon Mawar brought hurricane-force winds as it lashed Guam on Wednesday, snapping trees, raising fears of flash flooding and leaving most of the U.S. territory without power.

The storm, which packed the power of a Category 4 hurricane, was the strongest to hit the Pacific island in years and could intensify further Wednesday night, forecasters warned. The Guam Power Authority said the island’s power grid was providing power to only about 1,000 of its roughly 52,000 customers Wednesday afternoon and it was too dangerous for repair crews to venture outside.

There were no immediate reports of injuries. But the storm was so strong it broke the radar equipment that sends meteorological data to the local National Weather Service office — and sent the largest tree outside the building crashing into the driveway.

The roughly 150,000 people who live on Guam, an island nearly the size of Chicago located about 1,500 miles east of the Philippines, are used to tropical cyclones. The last major one, Super Typhoon Pongsona, made landfall in 2002 with the force of a Category 4 hurricane and caused more than $700 million in damage.

Stronger building codes and other advances have minimized damage and deaths from major storms on Guam in recent years. In most cases, “we’re just grilling, chilling, adjusting” when a tropical cyclone blows through, said Wayne Chargualaf, 45, who works at the local government’s housing authority.

But because it’s been so long since Pongsona, “We have a whole generation that has never experienced this,” he added. “So little doubt began to creep into my mind. Are we really ready for this?”

Mawar’s center appeared to be creeping westward over the northern part of Guam early Wednesday evening, said Brandon Bukunt, a Guam Weather Service meteorologist. Although the storm was unlikely to officially make landfall, he added, its dangerous southern eyewall was moving across the central and northern part of the island.

“The center doesn’t have to make landfall to get catastrophic or really impactful scenarios,” Bukunt said by phone, after the weather service issued a rare “extreme wind warning” for northern Guam on Wednesday night. Guam is 14 hours ahead of Eastern Time.

The storm’s slow pace, about three mph, increased the prospect of significant rainfall and flooding. A flood warning applied to early Thursday morning, and the weather service said in an update that it expected up to 25 inches of rain to fall in some areas.

President Biden declared an emergency for Guam on Tuesday, allow federal agencies to assist in relief efforts. Local officials also issued evacuation orders and grounded commercial flights.

The storm also affected the US military, which has a number of large installations on the island. All military aircraft there either left the island before the storm or were placed in protective hangars, said Lt. Cmdr. Katie Koenig of the US Navy said in a statement on Wednesday. All military ships also left, except for one ship that stayed in port with engine problems, she said.

Tropical cyclones are called typhoons or hurricanes depending on where they come from. Typhoons, which tend to form from May to October, are tropical cyclones that develop in the northwest Pacific Ocean and affect Asia. Studies say that climate change has increased the intensity of such stormsand the potential for destruction, as a warmer ocean provides more of the energy that fuels them.

Mawar, a Malay name meaning “rose”, is the second named storm in the western Pacific this season. The first, Tropical Storm Sanvuweakened in less than two days.

Mawar was expected to do so move towards the Philippines over the next few days, but not before leaving a path of destruction across Guam.

Carlo Sgembelluri Pangelinan, 42, who sells shipping containers at a store in Barrigada Heights, a hilly, affluent neighborhood near Guam’s international airport, said he doubted the storm would be worse than anything he had experienced.

Still, he added, he worried about people who didn’t have enough shelter, and animals without owners to care for them.

The population of the island is predominantly Catholicand the Roman Catholic Church in Guam said in a message to its congregations Wednesday that the fear and anxiety permeating the island was understandable, in part because Super Typhoon Pongsona had left an “indelible impression” that could still be felt more than 20 years later.

“There is good to be found in the midst of storms,” ​​the message said. “The kindness and care of people who show up during such trials is one of them.”

John Yoon, Victoria Kim, McKenna Oxenden and Jin Yu Young contributed reporting.