Radiation wafted from an earthquake-stricken nuclear power plant towards Tokyo on Tuesday, sparking panic in one of the world's biggest and most densely populated cities.
Women and children packed into the departure lounge at an airport, supermarkets ran low on rice and other supplies and frightened residents, tourists and expatriates either stayed indoors or simply left the city.
"I'm not too worried about another earthquake. It's radiation that scares me," said Masashi Yoshida, cradling his 5-month-old daughter Hana
The nail-biting eased in the afternoon after Chief Cabinet Secretary Yukio Edano appeared on national television saying radiation levels at the troubled Fukushima Daiichi nuclear-power complex had fallen dramatically since morning.
But confidence in the government is shaken and many decided not to take chances, especially after radiation levels in Saitama, near Tokyo, were 40 times normal -- not enough to cause human damage but enough to stoke fears in the ultra-modern and hyper-efficient metropolis of 12 million people.
Many hoarded food and other supplies and stayed indoors. Don Quixote, a multistorey, 24-hour general store in Tokyo's Roppongi district, was sold out of radios, flashlights, candles, fuel cans and sleeping bags on Tuesday.
At another market near Tokyo's Yotsuya station, an entire aisle was nearly empty on both sides, its instant noodles, bread and pastry gone since Friday's earthquake and tsunami killed at least 10,000 people nationwide and plunged Japan into a twin nuclear and humanitarian crisis.
At Haneda Airport, hundreds of young mothers lined up with children, boarding flights out of Tokyo.
"We are getting our of Tokyo and going to our home town because of the situation. For the time being we have bought a one way ticket and will wait and see what happens," said a Japanese woman with an eight-month-old baby and four-year-old son, who declined to be identified by name.
Tourists such as Christy Niver, of Egan, Minnesota, said they had enough. Her 10-year-old daughter, Lucy, was more emphatic. "I'm scared. I'm so scared I would rather be in the eye of a tornado," she said. "I want to leave."
Winds over the troubled Fukushima Daiichi nuclear-power complex, about 240 km (150 miles) north of Tokyo, blew slowly southwesterly towards Tokyo for much of the day before shifting westerly later, a weather official said.