A cyclone swept across Sri Lanka on Friday, leaving 46 people dead and 23 more missing, officials said, with the weather department warning the storm could intensify as it moves across the island over the next 12 hours.

Most fatalities were attributed to landslides triggered by torrential rainfall exceeding 300 mm (11.8 inches) over the past 24 hours as Cyclone Ditwah lashed the island nation, with the eastern and central regions most severely affected.

Nationwide, 43,991 people were evacuated to schools and other public shelters, the Disaster Management Centre (DMC) said in a statement, including families stranded on rooftops.

Schools remained closed, train services were suspended, and the Colombo Stock Exchange announced an early trading halt as heavy rains persisted.

“We are continuing rescue operations in the worst-hit areas, but some villages are difficult to reach because roads are blocked by landslides … we are doing our best to get everyone to safety,” Brigadier S. Dharmawickrema, Emergency Operations Director at the DMC, told Reuters.

Sri Lanka may divert flights from its main airport to Trivandrum or Cochin airports in south India if conditions worsen, Ports and Civil Aviation Minister Anura Karunathilake told reporters.

Local media reported that six flights, including from Muscat, Dubai, New Delhi, and Bangkok, had already been redirected from Colombo’s Bandaranaike International Airport (BIA).