Poland has reported that two missiles believed to have been fired by Russia struck Polish territory along its border with Ukraine on Tuesday, killing two people.

According to Polish radio ZET, two people died Tuesday afternoon after two projectiles struck Przewodów, a Polish village near the border with eastern Ukraine, causing an explosion.

The explosion prompted Poland, a member of the North Atlantic Treaty Organization(NATO), to convene an emergency national security meeting and elevate the military readiness level.

NATO Secretary-General Jens Stoltenberg tweeted that he spoke with Polish President Andrzej Duda about the explosion in Poland and that NATO is monitoring the situation and allies are closely consulting.

According to the BBC and CNN, the Russian defense ministry claimed that reports that the missiles were Russian are a "deliberate provocation," saying that the missile fragments filmed by the Polish media at the scene of the explosion have nothing to do with Russian weapons.

Russia fired about 100 missiles on Tuesday, most of them aimed at major Ukrainian cities, including Kiev. The barrage of missiles caused power outages in many cities across the nation, affecting some seven million households.