Russian missiles crossed into Polish territory on Tuesday, killing two people in an explosion that could threaten to pull the NATO alliance into the Ukraine war, a senior US intelligence official said.

The missiles struck Polish territory along its western border with Ukraine, the official with knowledge of the situation told the Associated Press. The strike happened near the village of Przewodów, some 45 miles north of the Ukrainian city of Lviv.

Piotr Mueller, a spokesman for the Polish government, did not immediately confirm the information, but said on Twitter that leaders in Warsaw were in a meeting over a “crisis situation.”

Polish radio station ZET reported that two stray missiles had hit the region, killing two people. The reports did not attribute the strikes to Russia or provide any further details.

The Pentagon said it could not immediately confirm the report of Russian missiles striking Poland.

“First, let me go ahead and highlight up front that we are aware of the press reports alleging that two Russian missiles have struck a location inside Poland near the Ukraine border,” Pentagon spokesman Gen. Patrick Ryder said at a briefing.

“I can tell you that we don’t have any information at this time to corroborate those reports and are looking into this further, and so when we do have an update to provide we’ll be sure to do so.”

Poland is a NATO member state. Should the Polish government decide to invoke article five of the alliance agreement — which calls for collective defense of member states — the strike could draw the additional 29 members of the Cold War era alliance, including the US, further into the conflict.

Asked how the US would respond if the strike was confirmed, Ryder declined to answer.

“I don’t want to speculate or get into hypotheticals,” Ryder said.

“When it comes to our security commitments, and Article Five, we’ve been crystal clear that we will defend every inch of NATO territory,” he added.

The attack came as Russia fired a salvo of nearly 100 missiles at Ukraine, targeting civilian infrastructure in the capital of Kyiv, but also striking targets in Western Ukraine, including in the Lviv province.

Additional reporting by Caitlin Doornbos and wires