Officials said the typhoon packed winds gusting up to 120 miles per hour (195 kph). Power supply to most of the Pacific island of 150,000 people was cut off early in the morning, shortly before the eye of the storm passed overhead.At least 39 people died in Micronesia earlier this week after Chata'an, which means rainy day in the local Chamorro language, caused heavy rain and mudslides there.
"It's unusual to be on the eighth floor of a moving building," said local resident Jon Anderson, who was in the Bank of Guam building during the storm. "I can't believe how much this building is moving."
Many electricity poles and trees were uprooted, some windows were shattered, and residents called the winds brutal and ferocious, local radio reported. Officials said it would be about three days before power was fully restored.
The territory cancelled Thursday's July 4 celebrations to prepare for the storm, with residents boarding up windows and stocking up on food and water. Heavily pregnant women were advised to move to hospital.
The measures helped ensure that there were no casualties, relief officials said.
By noon (0200 GMT), winds had dropped substantially although a typhoon warning was still in place, residents said. The local government planned to ask for federal assistance to repair damage to infrastructure and to fruit trees, officials said.