"NATO is monitoring the situation and Allies are closely consulting. Important that all facts are established," NATO Secretary General Jens Stoltenberg said on Twitter late Tuesday.
Stoltenberg also offered his condolences for the loss of life in Poland.
"Alarmed by reports of an explosion in Poland, following a massive Russian missile strike on Ukrainian cities," European Commission President Ursula von der Leyen said on Twitter.
Extending her condolences and support and solidarity with Poland and Ukraine, von der Leyen said: "We are closely monitoring the situation and are in touch with Polish authorities and partners and allies."
The UK meanwhile said it is “urgently” monitoring reports of missiles landing in Poland and is in touch with Warsaw and NATO allies, British Foreign Secretary James Cleverly said on Twitter.
At least two people were killed in a suspected missile attack in eastern Poland's village of Przewodow, a few kilometers from the border with Ukraine.
Radio Lublin reported that emergency services and representatives of the army are working at a farm’s grain drying site where the explosion occurred around 3.40 p.m. local time.
Police did not give the reasons for the explosion.
The explosion occurred 500-600 meters from a primary school. The area near the explosion site is closed.
If confirmed, this would be the first time someone has been killed on NATO territory as the result of a Russian strike. All NATO members are obliged to protect and defend every part of the alliance’s territory under Articles 4 and 5 of the alliance’s treaty.
Source: Anadolu Agency