The Indian Ocean tourist meccas of Mauritius and La Reunion braced Thursday for an intense tropical storm, Cyclone Garance, which was labelled a "direct threat" to the islands.
Mauritius shut its main airport the previous day, while the nearby French island of La Reunion was set to do the same on Thursday.
Garance was labeled a class 3 cyclone by Mauritius -- the second-highest alert level -- with gusts of up to 70 kph expected.
The Mauritius Meteorological Service said the cyclone was 310 kilometers northwest of the island and had increased to become an "intense tropical storm."
The cyclone is "dangerously approaching Mauritius and constitutes a direct threat," it said, adding that flooding was expected.
Garance was heading east but has curved south to pass between Mauritius and the French island of La Reunion, whose local prefect said it was set to declare a red alert and close its airport on Thursday.
The peak intensity of the cyclone was expected late in the day or into the night, French weather service Meteo-France said.
The "expected scenario is a direct impact on Reunion Island," said Celine Jauffray, of Meteo-France, on Wednesday, but said its intensity and path could still change.
Gusts of more than 150 kph were expected on the highest points of La Reunion, accompanied by heavy rain and rough seas.
A red alert would require the population to stay indoors and only emergency services could move around the island.
Schools were already closed from Wednesday afternoon.
Air Mauritius said all flights had been suspended "until further notice."