WARSAW, Poland (AP) — Experts from Ukraine have joined Polish and American investigators who are looking into a missile blast that killed two men in eastern Poland this week.

Ukrainian Foreign Minister Dmytro Kuleba said Friday that the Ukrainian experts were at the grain-drying facility in the Polish village of Przewodow where the missile landed Tuesday. The village is located about 6 kilometers (4 miles) from Poland's border with Ukraine.

“We will continue our cooperation in an open and constructive manner, as closest friends do,” Kuleba tweeted.

“I am grateful to the Polish side for granting them access,” he wrote.

Polish media reported seeing officials in Ukraine uniforms arriving at the site mid-day Friday.

On Tuesday, two workers were killed when a Russian-made projectile hit the grain-drying facility. Ukraine came under a heavy Russian bombardment that day.

NATO and Poland’s leaders have said the missile most likely came from a Ukrainian air defense system that fired in response to Russia’s attack. Ukrainian authorities initially said the missile was not theirs and asked to join the probe.

U.S. and Polish experts have been working at the site all week to establish the source and circumstances of the missile's launch. Poland's officials say there are camera recordings of the events leading up to the blast but they remain classified.

State funerals for the two men who died are expected over the weekend.

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