Russian authorities have said Ukrainian strikes killed six people, including three journalists, in the Luhansk region, while Ukraine reported 90 injuries, including 17 children, in Russian attacks on the Sumy region as the US said talks in Saudi Arabia have been going well and a positive announcement is expected soon.

A correspondent for the daily newspaper Izvestia, Alexander Fedorchak, and two employees of the Zvezda TV channel — cameraman Andrey Panov and driver Alexander Sirkeli — were killed in the strike, the Russian Investigative Committee said in a statement on Monday.

The committee added that it opened a criminal case following the incident.

A 14-year-old teenager and a correspondent for the Russian state news agency TASS, Mikhail Skuratov, were also injured, receiving shrapnel wounds.

Russian Foreign Ministry spokeswoman Maria Zakharova strongly condemned Ukraine's actions, pledging to seek a reaction from the Organization for Security and Cooperation in Europe (OSCE) and the United Nations Educational, Scientific and Cultural Organization (UNESCO), a specialised agency of the United Nations that promotes international collaboration through education, science and culture, aiming to build peace and sustainable development, to increase respect for justice, the rule of law, human rights and fundamental freedoms.

Commenting on the incident in a separate statement, the UN Secretary-General's office said the UN opposes the killing of journalists and wants such incidents to be thoroughly investigated.

Casualties in Ukraine

Ukrainian President Volodymyr Zelenskyy said Russian attacks targeted a school and residential buildings.

"There are a lot of wounded — as of now, we know about almost 90 people, including 17 children," Zelenskyy said in his daily evening address on social media, adding that rescue operations were still ongoing

He said that "school and residential buildings are at the epicentre" of the strike.

"Fortunately, the children at the school were in a shelter," he said.

Progressing talks

Despite the casualties, the US said the talks in Saudi Arabia are progressing well.

Reuters news agency cited a White House source saying that US-led talks in Saudi Arabia with delegations from Ukraine and Russia have been going well and a positive announcement is expected soon.

"Talks facilitated by the Trump administration’s technical teams in Riyadh are going extremely well, and all parties involved have been working all day and into the night. We expect to have a positive announcement in the near future," the source said.