A powerful typhoon sweeping toward southern Japan on Tuesday triggered the cancellation of hundreds of flights, with officials urging hundreds of thousands of people to seek shelter.

Typhoon Khanun was packing maximum sustained wind speeds of 180 kilometers per hour (112 miles per hour) as it crossed the Pacific Ocean toward Okinawa Prefecture.

The Meteorological Agency said the storm, which it described as "very strong," was about 170 km southeast of the regional capital of Naha at 2:45 p.m.

The center of the typhoon was expected to brush past Okinawa late Tuesday or early Wednesday before crossing to eastern China later in the week.

Cities across Okinawa advised more than 760,000 people to leave their homes as the weather agency warned waves of up to 12 meters (39-feet) high could pummel the group of islands.

The typhoon was expected to bring fierce winds and heavy rain. At least 180 millimeters (7.1 inches) of rain was expected to fall by noon on Wednesday, when the storm was likely to brush closest to Okinawa, NHK said.

"Many people stay at home because their houses are concrete," a disaster management official at the Okinawa regional government said, speaking on condition of anonymity.

"But we are asking people who live alone or in wooden houses in low-lying areas to consider seeking shelter before the typhoon gets bad."

More than 500 flights were canceled on Tuesday, while regional ferry and bus services were suspended ahead of the typhoon, NHK reported.

Japan Airlines and All Nippon Airways said more than 74,000 passengers in total would be affected by flight cancellations on Tuesday and Wednesday.