At least 16 people have been reportedly killed, including a child, and 20 others injured in Russian shelling of a market in the eastern Ukrainian city of Kostiantynivka, Donetsk region, President Volodymyr Zelenskyy said Wednesday.

The attack comes as U.S. Secretary of State Antony Blinken was visiting the capital Kyiv in a show of support for Ukraine's counteroffensive.

"At this moment, the artillery of Russian terrorists has killed 16 people in the city of Kostiantynivka, Donetsk region. A regular market. Shops. A pharmacy. People who did nothing wrong. Many wounded," Zelenskyy said in a social media post.

Prime Minister Denys Shmygal posted security camera footage of a blast tearing into rows of kiosks, sending residents running for cover and sending off car alarms. He said one child was among the dead.

Ukraine's Interior Minister Igor Klymenko said in a post on social media that the strike had left 28 people injured.

Kostiantynivka is a frontline town of an estimated 70,000 people in the eastern industrial region of Donetsk, which has been the epicenter of fighting since Russia launched its invasion in February 2022.

Donetsk has been partially controlled by Kremlin-backed separatists since 2014 and Russia claimed to have annexed the region alongside three others late last year.