BANGKOK (AP) — Floodwaters pressed toward Bangkok on several fronts Tuesday as soldiers and residents raced to pile sandbags and officials sounded a new alarm about vulnerable areas east of the capital near the international airport.

Much of the efforts in recent days have been aimed at shoring up defenses along Bangkok’s northern perimeter, facing the brunt of runoff from inland areas where Thailand’s worst flooding in a half-century has killed 315 people. Officials added concerns Tuesday about a new front: a flood plain near Suvarnabhumi Airport.

Droves of civilians joined soldiers in desperate dike-building efforts after Bangkok’s governor delivered a dramatic late-night TV warning that the city had until late Wednesday to lay down 1 million sandbags to protect an especially vulnerable 6-kilometer (3.7-mile) stretch.

“When the governor said we had 48 hours left, I thought we could not just wait until the water arrived, so I took a day off and volunteered,” said Suriya Termchoksap, 39, who took the day off from his job at IBM to help build a dike along a key canal.

North of the city of 9 million people, the government has meanwhile been fighting a losing battle against floods in communities where residents have been trapped on the upper floors of their homes.