More than a dozen airports across southern Russia suspended operations on Friday morning, while hundreds of flights were either cancelled or delayed after a Ukrainian drone crashed into the air traffic control center for the region, transportation authorities said.

The strike damaged equipment at the control center in Rostov-on-Don, which manages aviation for southern Russia, the Transportation Ministry said. No one was reported injured, but the attack forced the center to suspend work.

As a result, airports in southern Russia halted operations, including in the cities of Astrakhan, Vladikavkaz, Volgograd, Gelendzhik, Grozny, Krasnodar, Makhachkala, Magas, Mineralnye Vody, Nalchik, Sochi, Stavropol and Elista.

Aeroflot, Pobeda, Nordwind and Rossiya Airlines said they were adjusting their flight schedules for Friday and would need to cancel some flights. At least 14,000 passengers were stuck due to delays and cancellations, the Association of Tour Operators of Russia said.

Russia’s Transportation Minister Andrey Nikitin asked major airlines to coordinate with the state-owned Russian Railways and the Unified Transportation Directorate to arrange for trains and buses to transfer passengers from canceled flights.

The civil aviation agency, Rosaviatsia, initially issued a notice that flights in southern Russia could be suspended until May 12. The notice was rescinded later on Friday.