When Vadym Zgonnik was walking through the outdoor market in Kostyantynivka, Ukraine, with his wife and 6-year-old daughter on Wednesday afternoon, it was at first a bustling scene much like any other afternoon.
Then a huge fireball struck the market after a Russian missile attack, destroying several buildings, sending dozens fleeing for cover and killing more than a dozen others.
“I was pulling one woman,” said Mr. Zgonnik, 28. “I wanted to pull her into the building. Then I saw another woman burning. She was on fire; her leg was burning.”
He quickly fled with his wife and daughter.
By Wednesday evening, the death toll had reached 17, including one child. More than 30 other people were injured, two seriously, officials said. It was one of the deadliest strikes to hit Ukraine in months.
The attack clouded Secretary of State Antony J. Blinken’s unannounced visit to Kyiv, the Ukrainian capital, the same day, one of the highest-level visits by a U.S. official to there since President Biden visited in February. Mr. Blinken met with President Volodymyr Zelensky, announced more than $1 billion in new U.S. aid for Ukraine and praised its people’s valor and resilience in the face of what he called Russia’s “horrific” aggression.
The Ukrainian prosecutor’s office said that a search-and-rescue operation was underway Kostyantynivka and that some people remained under the rubble. The attack, it added, damaged 20 shops, as well as administrative and residential buildings.
Since launching its full-scale invasion of Ukraine more than 18 months ago, Russia has unleashed large-scale barrages of missiles, rockets and drones at cities and towns away from the front line, in a campaign intended partly to destroy civilian infrastructure and also apparently aimed to terrorize and demoralize the local population.
In June, a missile tore into a crowded restaurant that was popular with soldiers, foreign journalists and aid workers in Kramatorsk, 15 miles north of Kostyantynivka. That attack killed 13 people and injured dozens more.
The war has long been a daily reality in the city. It lies about 15 miles west of the frontline city of Bakhmut, which was captured by Russian forces in May. In April, Russian shelling killed six civilians in Kostyantynivka and wounded 11 others.
Denise Brown, the U.N. humanitarian coordinator for Ukraine, condemned the Wednesday attack in a statement, adding that intentionally directing an assault against civilians or launching one knowing it would cause disproportionate civilian harm was a war crime.
“International humanitarian law must be respected,” she said. “The people of Ukraine need this cruel devastation to stop.”
People had been wandering through a small maze of stores selling vegetables, local honey and hardware when the attack occurred. The aroma of rotisserie chicken and kebab was wafting past produce stands and clothing stalls. One shop sold Ukrainian military uniforms and other war-related items.
Mr. Zgonnik was near his own store, where he sold hot dogs, hamburgers and ice cream, when, around 2 p.m., he heard a piercing whistle over the usual chatter. And then, soon after, an explosion erupted.
By Wednesday evening, the dark smoky plumes from the fires had settled at the market, leaving scorched storefronts and charred wooden structures. The skeletal remains of singed vehicles were abandoned on mud and soaked sidewalks, where firefighters had extinguished buildings engulfed in flames. Reminders of the market’s earlier vibrancy lay scattered on the sidewalks amid pools of blood: baby wipes, produce stacked in boxes, a stray sandal.
About a dozen people stood behind police tape. Some were shopkeepers attempting to salvage what they could from the rubble. Mr. Zgonnik was among them, having returned to see what was left of his store and the market.
“The scary thing is that I know all the people who were there — all of them,” he said. “Three of them burned, just burned.”
Others at the site were searching for relatives, hoping they weren’t among the bodies lying in the rubble or being carried out by rescue workers in black body bags.
Pugach Olena, 26, said she believed one of her seven sisters, Samarkina Valeriia, who ran a stall at the market, had died in the attack.
Ms. Olena had been at home when she got a call from another sister about the blast. Terrified, she drove to the market.
“I arrived; it was all in smoke,” she said. “I ran; it was impossible to get there. I went around to the other side and saw that her kiosk was on fire. There were bodies lying there. Her kiosk and the one next to it were burned.”
Ms. Olena was told to look for her sister at the morgue.
It was hard to identify people there, she said. Two were so severely burned that they were unrecognizable. She brought her mother, and they both took DNA tests to help with an identification.
It will be two days, Ms. Olena was told, until the family will have its answer.
Anastasia Kuznietsova and Marc Santora contributed reporting.