Rescue workers in Taiwan battled through thick mud on Friday, looking for seven people still missing after Super Typhoon Ragasa this week sent a wall of water into a small town on the east coast.

The number killed in the flooding rose by one to 15, the fire department said.

Heavy rain in Hualien county caused a so-called barrier lake in the mountains to overflow on Tuesday, releasing a thick sludge of water and mud on the town of Guangfu.

While the flood waters have receded, large parts of the area remain covered in dark grey mud, creating problems for residents and rescuers alike.

‘NO TIME TO ESCAPE’

Rescue workers, sometimes wading in mud up to their waists, have been cutting holes in building roofs to check for missing people.

A man who gave his family name as Hwang said he was still looking for the body of his elder sister.

“She died in the house because it was completely filled with mud and there was no way to get her out,” he said.

Some elderly people died after they were unable to follow government orders to move upstairs and out of the way.

Huang Ju-hsing, 88, was trapped above his family-run grocery store after the flooding blocked access, but survived.

“There was no time to escape. We told him to hurry up and go upstairs,” said his wife Chang Hsueh-mei, who unlike her husband has been able to scramble over the wreckage downstairs and get outside.

“When you’re faced with an emergency, you suddenly find the courage to do anything,” said Chang, 78.

SEDIMENT-FILLED FLOOD WATERS

Taiwanese disaster expert Lu Jing-chien said the flood waters were unusual for Taiwan in that they carried so much sediment.

“Perhaps they didn’t expect that the water would carry such a high sediment load with sand and mud, and come so quickly and forcefully,” said Lu, an associate professor of disaster management at Central Police University.

What to do about the barrier lake, formed by earlier typhoons and which has now shrunk in size in terms of water volume to only 8% of what it was before the disaster, remains an unresolved issue.

Barrier lakes are formed when rocks, landslides or other natural blockages make a dam across a river, normally in a valley, blocking and holding back water, hindering or even stopping natural drainage.

The government has ruled out using explosives to break through the bank holding up the water, fearing it could bring more landslides and worsen the situation.

Mountainous, sparsely populated and largely rural, Hualien is one of Taiwan’s top tourist destinations due to its wild beauty.

The disaster did not affect Taiwan’s crucial semiconductor industry, located on the island’s west coast.