At least 75 people including five foreigners were killed and 100 more are missing and feared dead after a flash flood blamed partly on severe deforestation swept through the riverbank resort in North Sumatra late Sunday.

The swollen river also carried down hundreds of sawn logs from the slopes of nearby Mount Leuser. They smashed scores of frail tin-roofed bamboo homes and resort cottages, as well as concrete structures.

Langkat district chief Syamsul Arifin said the flood was caused by illegal logging inside the neighbouring Gunung Leuser national park and described it as a disaster waiting to happen.

The people of Bakorok, like millions of other Indonesians, are accustomed to annual rainy season floods -- worsened by the development of natural water catchment areas -- but nothing like this.

"I was asleep when the flood hit the area at 10 pm," said Tomira Sahuleka, 35, whose house was destroyed.

"Before the massive flood hit, I heard people shouting 'Flood!' and left home with my family.

"Had I been five minutes later my whole family would have been killed," he told AFP.

Nur Rahma, 35, was less fortunate. Three of her children aged 18 months, three and six are missing.

"I was still awake with my four children," a weeping Nur Rahma told AFP. "Before we could do anything the flood swept all of us away."

She and one of her daughters, aged four, managed to hold onto logs. "My other three children were swept away by the strong current."

Hundreds of paramilitary police and soldiers used chainsaws to clear logs and brought in earthmovers to remove motorbikes, pickup trucks and other debris which the flood tossed around the town.

Bridges were swept away. Police slung ropes connected to pulleys across the river for emergency crossings.

Residents estimated the height of the flood at two to three metres (seven to 10 feet.

On one side of the still swollen river, foreigners breakfasted outside at one resort -- gazing in wonder at the scene of devastation below.

"Help - six people," read a sign on the resort, showing that not everyone there had escaped unscathed.

The three latest bodies to be recovered were laid out in the mosque courtyard before being removed to a morgue in the city of Medan.

Headscarved women, sobbing quietly, watched the rescue effort and waited for news.

TERRA.WIRE