The Indian Ocean islands of Mauritius and La Reunion were on high alert Thursday for an intense tropical storm, Cyclone Garance, which was labelled a “direct threat” to the tourist destinations. Mauritius shut its main airport on Wednesday, while the nearby French island of La Reunion was set to do the same on Thursday.

Garance was labelled a class 3 cyclone by Mauritius — the second-highest alert level — with gusts of up to 70 kilometers (43 miles) an hour expected. The Mauritius Meteorological Service said the cyclone was 310 km (190 miles) northwest of the island and had 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 La Reunion, whose government representative said a “red alert” would be declared and the airport closed on Thursday. On its current trajectory, the cyclone was expected to pass within 50 km of La Reunion between Thursday evening and Friday morning, the prefecture said in a statement. Meteo-France warned there could still be a “direct impact” on Reunion and had earlier warned of gusts of more than 150 kph on the island’s highest points, 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 closed from Wednesday afternoon. Air Mauritius said all flights had been suspended “until further notice”.