Workers with a Danish aid organization who were helping to remove land mines in Ukraine were struck by a Russian ballistic missile on Thursday, killing two people and injuring three, according to a regional Ukrainian official.

“Today, Russians targeted workers of a humanitarian demining mission,” said Viacheslav Chaus, the governor of the Chernihiv region, north of Kyiv. A regional military official also reported the strike, though the national Ukrainian authorities have not confirmed it.

Mr. Chaus said that the workers were from the Danish Refugee Council, a group that has supported demining efforts across Ukraine.

In a statement, the group said that one of its demining teams “was impacted during operations in Chernihiv today.” It added: “Emergency response procedures were immediately activated, and we are working closely with the relevant authorities to assess the situation and ensure the safety of our staff.”

The council did not say whether any of its staff members had been killed or injured.

A post on Facebook by Dmytro Bryzhynsky, the military administrator of the city of Chernihiv, showed demining workers in blue vests running from smoke in a field.

Ukraine is among the most heavily mined countries in the world. More than 20 percent of Ukrainian territory is potentially mined, according to a United Nations Development Agency report published in May.

The missile strike came as President Volodymyr Zelensky was visiting Paris to meet with European leaders who are discussing potential security guarantees for Ukraine, including possibly deploying European troops into the country.