A Polish Air Force MIG-29 fighter jet during the annual air show in the second and final day of the Radom International Airshow at Radom's Sadkow Airport in Radom, Poland, on 27 August 2017. (Photo: EPA-EFE / Jacek Turczyk POLAND OUT) 
By Alan Charlish and Lidia Kelly
"During today’s attack by the Russian Federation targeting objects on the territory of Ukraine, our airspace was repeatedly violated by drone-type objects," Poland's military command said in a statement.
"An operation is underway aimed at identifying and neutralizing these objects ... weapons have been used, and service personnel are carrying out actions to locate the downed objects."
It said the military operation was ongoing and urged people to stay at home, naming the regions of Podlaskie, Mazowieckie, and Lublin as most at risk.
"The Operational Command of the Polish Armed Forces is monitoring the situation, and subordinate forces and units remain on full readiness for immediate response," it added.
Poland also closed four airports including its main Chopin Airport in Warsaw, according to the U.S. Federal Aviation Administration. There was no official confirmation from Polish authorities that any airports had been closed.
The U.S. Federal Aviation Administration said the Rzeszow–Jasionka Airport in Poland's southeast, a hub for passenger and arms transfers to Ukraine, was among the airports that had been temporarily closed.
Russia's defence ministry did not immediately respond to Reuters' request for comment.
Earlier, Ukraine's air force reported that Russian drones had entered NATO-member Poland's airspace, posing a threat to the city of Zamosc, but it subsequently removed that statement from the Telegram messaging app.
In the United States, Democratic Senator Dick Durbin said repeated violations of NATO airspace by Russian drones were a sign that "Vladimir Putin is testing our resolve to protect Poland and the Baltic nations."
"After the carnage Putin continues to visit on Ukraine, these incursions cannot be ignored," he said on X.
Poland has been on high alert for objects entering its airspace since a stray Ukrainian missile struck a southern Polish village in 2022, killing two people, a few months into Russia's full-scale invasion of Ukraine. But there have been no reports of Polish or allied defence systems destroying drones.
As of 0220 GMT, most of Ukraine, including western regions of Volyn and Lviv, which border Poland, had been under air raid alerts for several hours, according to Ukraine's air force.
(Reporting by Lidia Kelly in Melbourne, David Shepardson and Andrea Shalal in Washington and Alan Charlish in Warsaw; Writing by Lidia Kelly; Editing by Stephen Coates)