TOKYO — Japan woke on Sunday morning to flooded rivers and burst levees, as emergency workers used helicopters and boats to rescue stranded residents from their homes in the wake of Typhoon Hagibis, the largest storm to hit the country in decades.

Rain began falling on Saturday and continued through Sunday morning, testing dams, pulling down hillsides, destroying roads and bridges, and driving rivers over their banks.

How many people are affected?

Anticipating extensive damage, the authorities urged nearly six million people to evacuate.

Rescue services jumped into action early in the morning, with helicopters plucking stranded people from balconies and roofs. At least 35 people were killed, with 15 people reported missing and at least 100 injured, according to the Kyodo news agency. Deaths were expected to mount as swollen rivers rushed through flooded neighborhoods.