German Chancellor Olaf Scholz said in a statement on Wednesday that he had spoken with Polish President Andrzej Duda and expressed his condolences to him and his citizens after blasts near Poland’s border with Ukraine.

“This is a terrible incident and it is necessary to carefully clarify how it came about,” he said, according to the statement.

Biden says missile that killed two in Poland may not have come from Russia

Poland has called the blasts a strike by a Russian-made projectile, while Russia has denied the claim.