Help is starting to pour into Thailand and other parts of Asia where rising floodwaters are swamping entire communities and threatening to overrun even more.

United States Marines arrived in Bangkok Saturday with equipment, sandbags and other relief supplies. The U.S. ambassador to Thailand said the Marines will work with the Thai military to battle floodwaters that have hit 61 of Thailand's 76 provinces.

Officials say almost 300 people have died in Thailand, most of them north of Bangkok, in and near the ancient temple city of Ayutthaya.

Much of Ayutthaya remained under water Saturday, driving some residents – and their pets – to the rooftops of homes to stay dry. In less affected areas, where water was only waist deep, relief crews in boats distributed supplies to stranded residents.

A Dutch volunteer said many people in Ayutthaya have no electricity, food or water; others are sick and have no means of getting out.

Workers at the Bang Pa-in industrial center in Ayutthaya province tried to keep out rising water but had to abandon the effort Saturday. News reports say the complex hosted more than 90 manufacturers of auto parts, electronics, garments and plastics.

Thais who doggedly stayed by their homes on Koh Kred Island tried to make their way through floodwaters that were chest- or neck-high.

Aid from China arrived Saturday in Cambodia, where flooding and landslides have killed 247 people. A Cambodian government spokesman said the relief supplies will go to hospitals in the hardest-hit areas.

Torrential rains and flooding are also being blamed for deaths in Vietnam and the Philippines.