Ukrainian airspace was restricted for civilian flights as Russia started attacking Ukraine early in the morning on Thursday.

Airlines including Qatar Airways, Wizz Air, Turkish Airlines and others have canceled Kyiv flights scheduled for Thursday. The flights were restricted “due to potential hazard for civil aviation,” said the notice posted on a Federal Aviation Administration website.

The European Union Aviation Safety Agency (EASA) said airspace in Russia and Belarus within 100 nautical miles of their borders with Ukraine could also pose safety risks.

“In particular, there is a risk of both intentional targeting and misidentification of civil aircraft,” the agency said in a conflict zone bulletin.

“The presence and possible use of a wide range of ground and airborne warfare systems pose a high risk for civil flights operating at all altitudes and flight levels.”