Here are top 10 developments from this big story
The rocket fell at Przewodow, a village in eastern Poland about 6 km from the border with Ukraine, the Polish foreign ministry said. Media reports said the strike hit a grain-drying facility.
Soon after the attack, the Polish foreign ministry said the missile was Russian-made and summoned Russia's ambassador to Warsaw for "immediate detailed explanations".
The Russian defence ministry, however, denied any role in the missile strike and accused the Polish mass media and officials of "deliberate provocation to escalate situation".
The blast prompted an emergency meeting at the G20 summit currently underway at Bali, Indonesia. The meeting led by US president Joe Biden was attended by major NATO powers and Japan.
Following the meeting, Biden said the US and its NATO allies are investigating the blast that killed two in Poland, but early information suggests it may not have been caused by a missile fired from Russia.
Poland president Andrzej Duda, too, said there was no clear evidence of who fired the missile, adding that it was "most probably Russian-made". "We do not for the moment have unequivocal evidence of who fired the missile," he said.
Earlier, Warsaw put its military on high alert after an emergency national security council meeting. "There has been a decision to raise the state of readiness of some combat units and other uniformed services," spokesman Piotr Muller told reporters.
Ukrainian President Volodymyr Zelensky had earlier said two Russian missiles hit Poland in what he described as "a very significant escalation".
The blast had drawn widespread condemnation, with European Union chief Charles Michel saying he was "shocked" and French President Macron calling for talks at the G20 summit.
Ukraine's Foreign Minister Dmytro Kuleba had earlier rejected as a "conspiracy theory" the idea that the Poland blast may have been caused by a surface-to-air missiles fired by Kyiv's forces.
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