The blast set off tense moments with world powers as Russia’s war in Ukraine rages on.
The Polish government convened an emergency security and defense meeting Tuesday and agreed to increase its military readiness, government spokesman Piotr Mueller said, after an explosion killed two people near the border with Ukraine.
It was not clear what caused the explosion in the southeastern town of Hrubieszów, Mueller said after the emergency meeting was convened.
"A moment ago it was decided to increase the readiness of some military units in Poland and other uniformed services," he told reporters.
Unconfirmed news reports that the blasts were caused by Russian rockets hitting a town a few miles from Ukraine — whether intentional or by mistake — raised fears of an escalation in President Vladimir Putin’s war.
“We’ve seen these reports out of Poland and are working with the Polish government to gather more information,” the spokesperson for the National Security Council said in a statement. “We cannot confirm the reports or any of the details at this time. We will determine what happened and what the appropriate next steps would be.”
Russia pushed back on the allegations soon after the reports emerged.
“The statements of the Polish media and officials about the alleged fall of ‘Russian’ missiles in the area of the settlement of Przewodow, is a deliberate provocation in order to escalate the situation,” the Russian Ministry of Defense said in a statement on Telegram, referring to the village widely reported to have been hit.
The increasingly urgent situation comes as Russia launched an intense wave of airstrikes on cities across Ukraine on Tuesday, forcing widespread blackouts and hitting residential buildings in the capital, Kyiv.
The barrage targeted key cities from Lviv in the west to Kharkiv in the northeast, pounding energy infrastructure and knocking out power to vast areas in one of the largest coordinated attacks of the war.
“It is only a matter of time before Russian terror goes further. The longer Russia feels impunity, the more threats there will be to anyone within reach of Russian missiles,” Ukrainian President Volodymyr Zelenskyy wrote on Telegram. “This is a Russian missile attack on collective security! This is a very significant escalation. We must act.”
The prospect of Russian missiles possibly hitting Poland, a member of NATO, triggered fears that the war in Ukraine could intensify sharply.