BANGKOK Thailand's catastrophic floods may take up to six weeks to recede, the prime minister said Saturday, as residents living in Bangkok's outskirts sloshed through waist-high waters in some areas and the human toll from the crisis nationwide rose to 356 dead and more than 110,000 displaced.

Water bearing down on the capital from the north began spilling through Bangkok's outer districts on Friday and continued creeping in on Saturday. So far, however, most of the metropolis of 9 million people has escaped unharmed, and its two airports are operating normally.

Bangkokians are girding for the worst, though, after Prime Minister Yingluck Shinawatra this week urged all residents to move valuables to higher ground.

A mild panic prompted a run on grocery stores, with many running out of bottled water. The government's emergency relief center said flooding in the city was occurring at "concentrated points." One of them, the northern district of Don Muang, was partially inundated after floodwaters burst through a canal barrier wall that workers were scrambling to repair overnight.

Don Muang is home to the capital's second airport, as well as the government flood relief center. But some residents in swamped areas there said they were running short on food. Volunteers who had been preparing to send emergency supplies to Ayutthaya, a city north of Bangkok that has been submerged for more than two weeks, were forced to consume them instead.

"Now we've become flood victims" ourselves, said 53-year-old Pimnipha Na Bangchang. "We're distributing this food aid to our community because we haven't received any help."

Excessive monsoon rains have flooded a third of the Southeast Asian nation since late July, causing billions of dollars in damage and putting nearly 700,000 people temporarily out of work.

Some flooding in Bangkok's outskirts was expected after Yingluck ordered floodgates opened Thursday in a risky move to drain the dangerous runoff through urban canals and into the sea. Nobody knows with any certainty to what extent the city will flood.

In a weekly radio address Saturday, Yingluck said "during the next four to six weeks, the water will recede."

In the meantime, the government will step up aid to those whose lives have been disrupted, including 113,000 people living in temporary shelters after being forced to abandon submerged homes, she said.

The flooding is the worst to hit the country since 1942, and the crisis is proving a major test for Yingluck's nascent government.