The US territory of Guam has been smashed by the powerful Typhoon Mawar, lashing the Pacific island with high winds and heavy rain, tearing down trees, walls and power lines.

Key points:

• Typhoon Mawar made landfall in Guam at about 9pm last night
• Authorities have so far reported no deaths or injuries
• Guam is a crucial hub for US forces in the Pacific, and the Department of Defense controls about a third of the island

The typhoon, the strongest to hit the territory of roughly 150,000 people since 2002, briefly made landfall on Wednesday night as a category 4 storm at Andersen Air Force Base on the northern tip of the island, according to National Weather Service meteorologist Patrick Doll.

Videos posted on social media showed fallen trees, a flipped ute, solar panels flying through the air, parts of a hotel's exterior wall crumbling to the ground, and storm surge and waves crashing through coastal reefs.

Electricity to most of the island was knocked out, and the Guam Power Authority said it was too risky for repairs crews to venture out, leaving residents facing a long, dark night of noisy and dangerous weather.

"It's going to be scary. There's no electricity unless you have a generator [or] partial generator. Reassure your children," Brandon Aydlett, a National Weather Service operations officer, told a briefing, according to The Guam Daily Post.

At one of the island's many hotels, the 30-floor Dusit Thani Guam Resort which houses around 300 guests, desk clerk Casey Hattori said the lobby was flooded with a foot of water.

Outside, trees snapped in howling wind.

"I can hear the walls shaking. The wind is super strong. I can hear it whistling as it comes through the cracks of the doors," Ms Hattori told AFP.

"Lots of Guam is dealing with a major mess that's going to take weeks to clean up," he added.

J Asprer, a police officer in the Dededo precinct in northern Guam, said before dawn that he had not received any reports of injuries but several police cars and personal vehicles had been damaged by debris, and uprooted trees made some roads impassible.

Most of the calls overnight came from worried people off-island who were unable to reach family members, Mr Asprer said.

US navy deployed to help recovery effort

The US navy has ordered the USS Nimitz aircraft carrier strike group to head to the island to assist in the recovery effort.

The Nimitz, along with the USS Bunker Hill, a cruiser, and the USS Wayne E Meyer, a destroyer, were south of Japan and expected to arrive in Guam in three or four days, said a US official, who spoke on condition of anonymity to discuss ship movements not yet made public.