A screen grab from the video shows people being trapped by flames. [Photo/IC]

TAIPEI - The number of people injured in an explosion and fire in a recreational water park in Taiwan has been revised down to 498, the local health department said Sunday.

Authorities began investigating the cause, suspected to be a sudden explosion of a coloured powder thrown on those attending the party.

The revision was made after the New Taipei city health bureau cleared overlapping calculations due to transfers of patients to other hospitals.

A total of 202 people are severely injured, but no deaths are reported yet, according to the New Taipei city health bureau.

Among the injured are two students from the Chinese mainland, five from Hong Kong and six foreigners.

Most of the victims suffered severe burns or have inhaled large amounts of black carbon dust. The injured are being treated in 43 local hospitals.

The island's health department has launched an emergency response routine, calling for medical institutions in nearby cities including Taipei and Keelung to help treat the injured.

A total of 183 patients in intensive care need urgent skin-grafts, said Wang Tsung-hsi, director of the medical affairs bureau of Taiwan's health and welfare department, earlier on Sunday.

The bureau has sent out urgent calls to organ donation centers and the plastic surgery medical association for donated skin, artificial skin and albumin among other biological necessities.