HAGATNA, Guam -- Guam is cleaning up after a powerful Pacific typhoon hammered the U.S. territory with high winds, rain and large waves.

Workers in Mongmong, Toto and Maite villages used a pickup to tow away downed coconut trees on Saturday.

A large monkeypod tree was uprooted and sitting on its side at a park in the capital of Hagatna.

One person was injured in the storm and taken to the hospital.

"There were no casualties. That means people really paid attention," said Veronica Verde, spokeswoman for Federal Emergency Management Agency, Region 9.

Verde said FEMA will do a joint assessment with the government of Guam on damage from the typhoon. The assessment will be compiled to determine if any federal funding will be needed.

Gov. Eddie Calvo's spokeswoman, Oyaol Ngirairikl, said the government was still in its initial stages of assessing damage.

Navy Lt. Tim Gorman, spokesman for Joint Region Marianas, said he lost power about 8 p.m. Friday but the electricity came back on at noon.

"All things considered, it could have been a lot worse," he said.

About 40 per cent of the island's 50,000 electric utility customers were still without power in the early afternoon, said Heidi Ballendorf, a spokeswoman for Guam's power and water utilities. Service had yet to be restored to about 12 per cent of water customers.

A 57-year-old homeless man said he rode out the storm on the grounds of a strip mall in the capital of Hagatna. Frank Reyes said the storm was the worst he's experienced since becoming homeless two years ago.

"This one was the strongest so far. This one kind of scared me," Reyes said.

Hagatna resident Roberta Perez, 57, said she was surprised the road in front of her house didn't flood. She prepared for the storm by doing work inside and outside her house.

"I secured all my personal belongings, and I cut my mango tree down because that saves me from a lot of work," Perez said. But her neighbour's pandanus tree fell, which affected her property. "In order for me to access my driveway, I have to clean this up."

The typhoon was 265 kilometres northwest of Guam as of 7 a.m. local time. It had maximum sustained winds of 205 kph.

It was travelling west-northwest but is expected to curve and start heading northeast.

National Weather Service meteorologist Patrick Chen said the storm has the potential to become a super typhoon when it's over the open ocean.

He said residents should avoid beaches for the next couple of days because the storm will continue to generate swells and high surf for Guam's coastlines.

Guam is home to about 160,000 people. It is known for white beaches and historic World War II battle sites, and it depends heavily on tourism.