Winds and rain began to batter Guam Wednesday as a life-threatening typhoon approached, a storm potentially so severe that President Joe Biden signed an emergency declaration Tuesday to mobilize resources.

Super Typhoon Mawar is expected to be a «triple threat» of torrential rain, life-threatening storm surge and Category 4 hurricane force winds, according to Guam’s Department of Homeland Security.

“This is a very serious situation with constantly deteriorating conditions,” the department said.

Forecasters said sustained winds of more than 50 mph and gusts of more than 70 mph have been felt.

The storm’s track moved slightly to the north but is forecast to cross Wednesday afternoon or Wednesday night local time, said Landon Aydlett, warning coordinator for the National Weather Service.

«Everyone is going to feel this, and they’re going to feel it for a while,» Aydlett said in a live broadcast Wednesday afternoon. He urged people to stay inside.

It was about 40 miles east-southeast of Guam at 2 p.m. local time (early midnight Wednesday ET). said the weather service. Winds were measured at around 135 mph. The storm was moving slowly, about 3 mph to the northwest.

Typhoon warnings have been issued for Guam and Rota. Typhoon-force winds extended 50 miles from the center of the storm, and tropical storm-force winds reached up to 140 miles from the center, the weather service said in an update at 1 p.m. local time.

Satellite image showing Typhoon Mawar approaching Guam.NASA via AP

Loss of power and access to water is likely to last for days, if not weeks, after the storm passes. The flights were canceled from Tuesday to Wednesday, according to the island’s national security.

Mawar is expected to be the first «ocular passage» on Guam since December 2002, the weather service said. Approximately 170,000 people live there.

That storm was Super Typhoon Pongsona, which had sustained winds of 144 mph and caused an estimated $700 million in damage, according to a NOAA report.

Luis Zamora, 40, is an electrical engineer who frequently visits the island from California for his work with the US military and is taking refuge in a hotel with his colleagues. He was scheduled to leave on Thursday, but on Tuesday he received notification from United Airlines that his flight was cancelled.

«Overnight, you can definitely see the difference in the wind,» Zamora said. «You can hear it much louder…you can see the trees moving.»

Originally from Florida, Zamora has prepared the same way he would for a hurricane: a bathtub full of water, charging his devices before a power outage and stocking up on non-perishables. He also trusts the staff at his hotel, the Dusit Beach Resort, who have assured guests of their food stock and emergency plans.

«I think Guam is way ahead of, you know, storm preparedness,» Zamora said. «It’s just that the result is something you can’t really prepare for.»

Zamora and her colleagues are just a 10-minute drive from the airport, but it’s unclear how quickly they could get home after the storm passes.

«It’s about how much damage it’s going to do and when everything is going to be able to work again.»

Governor of Guam, Lou Leon Guerrero signed an executive order order evacuations from low-lying areas and mobilize the national guard to help get people to shelters. In a letter to Biden, Guerrero warned that the typhoon is expected to cause «substantial destruction on our island.»

“I anticipate that this situation will be of such severity and magnitude that an effective response will be beyond the capacity of the Government of Guam and supplemental federal assistance will be necessary to save lives and protect public property, health and safety, and mitigate the effects of this impending catastrophe,” Guerrero said in the letter, which was posted on Instagram.

In a speech on YouTube, Guerrero urged people to stay at home and take steps to prepare.

“I know it’s been a long time since we’ve had a storm of this magnitude and it’s terrifying,” Guerrero said. «I ask you to remain calm, stay informed and most importantly, be prepared.»

Janhvi Bhojwani , The Associated Press and phil helsell contributed.