Flash floods triggered by torrential rain have wreaked havoc in the Mauritian capital Port Louis killing at least 11 people.

Most of the victims on the Indian Ocean island were trapped in underground areas due to rapidly rising floodwaters. One of the victims died of a heart attack.

The floods have paralysed the transportation system in Port Louis bring the normal life of scores of people to a halt.

"The roads are blocked and there is mud everywhere. Trees have fallen all over the place. If people couldn't rely on their neighbours so much to help them, then we would have lost more lives. I am so angry at the authorities," Ameeksha Dichand, a resident in Port Louis, told BBC.

Nearly 152 millimetres of rain has been recorded in less than an hour and a half, said meteorological officials. Average rainfall in March, the wettest month for the island, is generally around 220 millimetres.

"We had forecast bad weather and rain, but not on that scale and not in such a short period of time," said Balraj Dumputh, the chief of the meteorological service, according to AFP.

A day of mourning is being observed on the island over the disaster.

Prime Minister Navinchandra Ramgoolam , in a national radio address, said climate change is badly affecting the country.

Torrential rains are expected to continue in the coming days and people have been urged to stay indoors.

"It's unprecedented. We have to adapt to this situation and to the damage caused by nature," said Patrick Assirvaden, the head of the ruling party, although there is no official reaction from the government.