By Marek Strzelecki and Dan Peleschuk
WARSAW/KYIV, Ukraine (Reuters) - Two people died in an explosion in a Polish village near the border with Ukraine on Tuesday, firefighters said, with NATO allies investigating unconfirmed reports the blast was caused by stray Russian missiles.
The explosion occurred after Russia hammered cities across Ukraine with missiles on Tuesday, attacks that Kyiv said were the heaviest wave of strikes nearly nine months into the Russian invasion. Some hit the western city of Lviv, less than 80 km (49.7 miles) from the border with Poland.
Poland is a member of the U.S.-led Western military alliance NATO, which is committed to collective defence, and the possibility that the Polish explosion resulted from an intentional or accidental Russian strike raised alarm.
A NATO official said the alliance was looking into the reports and closely coordinating with Poland.
The Associated Press cited a senior U.S. intelligence official as saying the blast in the eastern Polish village of Przewodow was caused by Russian missiles crossing into Poland.
In Washington, the Pentagon and the U.S. State Department said they could not confirm Russian missiles had landed on Polish territory.
"We are aware of the press reports alleging that two Russian missiles have struck a location inside Poland near the Ukraine border. I can tell you that we don't have any information at this time to corroborate those reports and are looking into this further," Pentagon spokesperson Brigadier General Patrick Ryder said.
Russia's defence ministry denied reports that Russian missiles had landed in Poland, describing them as "a deliberate provocation aimed at escalating the situation".
Polish Prime Minister Mateusz Morawiecki called an urgent meeting of a government committee for national security and defence affairs on Tuesday night, government spokesman Piotr Muller said on Twitter.
Polish Radio ZET reported that two stray missiles hit Przewodow, killing two people, without elaborating. The village is 6 km (3.5 miles) from the border with Ukraine.
Ukrainian President Volodymyr Zelenskiy said, without providing evidence, that "Russian missiles hit Poland."
Senior officials from Germany, Norway, Lithuania and Estonia - all NATO members - said they were trying to glean more information together with Poland and other allies.
"This is a very serious incident but much remains unclear," Norwegian Foreign Minister Anniken Huitfeldt said.
EXPLOSIONS ACROSS UKRAINE
Air raid sirens blared and explosions rang out in nearly a dozen major Ukrainian cities, echoing a pattern in recent weeks of Moscow lashing out far from the front after losses on the battlefield, most recently the major southern city of Kherson.
Russia had launched 110 missiles and 10 Iranian-made attack drones into Ukraine by early evening, Ukraine's armed forces General Staff said in a statement.
Zelenskiy said the main target of the missile flurry was energy infrastructure, as before, though added that only 10 intended targets in all had been hit.
"It's clear what the enemy wants. He will not achieve this," he said in a video address on the Telegram messaging app. Kyiv has said such strikes only stiffen its resolve to repel Russian forces that invaded in February.
In the capital Kyiv, flames funnelled out of a five-storey apartment block after being hit by what residents said appeared to be shot-down pieces of missile. The emergency service said one person was confirmed killed and another injured. Kyiv's mayor said half the capital was left without electricity.
Other strikes or explosions were reported in cities ranging from Lviv and Zhytomyr in the west to Kryvy Rih in the south and Kharkiv in the east. Regional officials reported some of the attacks had knocked out electricity, water and heating.
The attacks had left millions of Ukrainians without energy in 16 of the country's 24 regions including Kyiv, the U.N. humanitarian office (OCHA) said in a statement.
BUNKERS ABANDONED
Just four days ago Russian troops abandoned Kherson city in the south, the only regional capital Moscow had captured since its invasion, and six weeks after President Vladimir Putin declared it an eternal part of Russia.
Moscow had said last week its troops would occupy positions easier to defend on the opposite bank of the Dnipro River that bisects Ukraine. But video images filmed in the town of Oleshky, across a collapsed bridge from Kherson, appeared to show Russian forces had vacated their bunkers there too.
Further east, Russian-installed administrators said they were pulling civil servants out of Kherson province's second biggest city, Nova Kakhovka, on the river bank next to a huge, strategic dam.
Natalya Humenyuk, a Ukrainian military spokesperson, said Moscow seemed to be repositioning troops and artillery 15-20 km (10-15 miles) further from the Dnipro, to protect its guns from Ukrainian counter-strikes.
Russia had artillery still capable of striking Kherson from those new positions, but "we also have something to answer with", she said.