Polandsaidit scrambled fighter jets and shot down an unspecified number of Russian drones that crossed into its airspace, calling it "an act of aggression."

The drones repeatedly violated Polish airspace early September 10, the military said in a statement, after Russia launched a wave of strikes on targets in Ukraine, including near the Polish border.

There were no immediate reports of casualties in Poland, and it was unclear many drones had crossed into Polish airspace. The military said it was searching for downed objects.

This is an act of aggression that posed a real threat to the safety of our citizens, the militarys operational commandsaid in a post to X.

The incident sent tensions spiking in Warsaw, and other members of the NATO military alliance. Polish officials said they were in contact with NATO officials.

There was no immediate comment from Russia's Defense Ministry.

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Poland said it had also closed four airports, including the country's main airport Warsaw. The US aviation regulator, the Federal Aviation Administration, issued an advisory saying the RzeszowJasionka Airport in the southeast, had also been closed. The facility is a hub for passenger and arms transfers to Ukraine.

Most of Ukraine, including the countrys western regions of Volyn and Lviv, was under an air raid alert in the early hours of September 10, according to Ukraine's air force.