A powerful storm caused by a rapidly growing low-pressure system pummeled much of the nation Saturday, injuring at least two people, one of them critically, and wreaking havoc with transportation systems as it plowed northward.

The Meteorological Agency said heavy rain pelted the archipelago's Pacific coast and was likely to reach northern Japan on Sunday, with Hokkaido expected to see more than 50 mm of precipitation per hour from Sunday morning through evening. The agency also issued a tornado advisory for Yamanashi, Shizuoka, Aichi, Tokushima and Kochi prefectures.

In Tottori Prefecture, two South Korean tourists riding bicycles were injured Saturday after being knocked to the ground by strong gusts. One of them, a woman, was in critical condition, police said.