BANGKOK (AP) — Bangkok residents jammed bus stations and highways on Wednesday to flee the flood-threatened Thai capital, while others built cement walls to protect their shops or homes from advancing waters surging from the country’s flooded north.

“The amount of water is gigantic,” Prime Minister Yingluck Shinawatra said. “Some water must spread into Bangkok areas but we will try to make it pass through as quickly as possible.”

Some neighborhoods on the city’s fringes were already experiencing waist-high flooding, but central areas remained dry.

Flood waters breached barriers protecting Bangkok’s second largest airport on Tuesday, halting commercial flights and underlining the gravity of the Southeast Asian nation’s deepening crisis, which has seen flood waters inundate a third of the country and kill 366 people over the last three months.

Yingluck’s government declared a five-day public holiday on Tuesday in affected areas, including Bangkok, while the Education Ministry ordered schools to close until Nov. 7. Many anxious city residents were taking advantage of the holiday to leave the capital or prepare for a possible watery siege.

Panic buying of food and other necessities emptied the shelves of many supermarkets, and walls of sandbags or cinderblocks covered the entrances of many buildings.