U.N. Secretary-General António Guterres has arrived in Ukraine for talks with President Volodymyr Zelensky. The trip follows Guterres’s visit to the Kremlin, where on Tuesday Russian President Vladimir Putin promised “in principle” that Russia will allow civilians to evacuate from conflict zones. Ukrainian officials dispute that, saying convoys attempting to flee through humanitarian corridors continue to come under fire.

In Mariupol, the commander of the city’s remaining Ukrainian forces pleaded in a new video for an international rescue operation to evacuate troops and civilians from the massive steel plant where they remain holed up against a withering assault by Russia’s military.

Serhiy Volyna: “Here with us there are hundreds of civilians, including tens of children. There are many people with reduced mobility, many elderly. The situation is very difficult. There are shortages of water, food, as well as ammunition, weapons and military equipment.”

In southern Ukraine, Russian soldiers opened fire with tear gas and stun grenades on a crowd of peaceful protesters who’d gathered to demand an end to Russia’s military occupation of their city. Elsewhere, in Kherson, one person was killed Wednesday as rockets fell on a residential neighborhood.