WARSAW, Poland (AP) — Poland’s government on Friday called the killing of a Polish aid worker by Israeli airstrikes in Gaza a murder, and demanded Israel’s support for a Polish investigation into the case.

Deputy Foreign Minister Władysław Teofil Bartoszewski told lawmakers in parliament that the April 1 death of Damian Soból, 35, and six other workers of the World Central Kitchen charity who were distributing food in Gaza was “shocking and disturbing.”

Poland expects Israel’s “full cooperation” in the investigation opened by Polish prosecutors in Soból’s hometown of Przemyśl in Poland’s southeast, Bartoszewski said. The prosecutors “have classified it as a murder,” he said.

Israel conducted a speedy investigation and took responsibility for the deaths, but said the attack that killed the aid workers and their Palestinian driver was a tragic mistake. It shared the findings with the countries that lost citizens in the attack. The Israeli military dismissed two officers and reprimanded three others, saying they violated the army’s rules of engagement.