CHERNIHIV, Ukraine (AP) — A Russian missile attack in the center of a northern Ukrainian city on Saturday killed seven people and wounded over a hundred others, including children, Ukrainian officials said.

The attack in Chernihiv happened as Ukrainian President Volodymyr Zelenskyy arrived in Sweden on his first foreign trip since attending a NATO summit in Lithuania last month.

Images of the aftermath showed badly damaged buildings including a theatre with its roof blown away, mangled cars and survivors walking amid the debris with bloodstained clothes. The dead in the daytime strike included a 6-year-old girl, while 15 children were among the 129 wounded, Ukraine’s Interior Minister Ihor Klymenko said.

The square in front of the theater building had been bustling with life, with people returning from church after celebrating the Apple Feast of the Saviour religious holiday, baskets of consecrated apples in hand, Klymenko said. Following the strike, debris from the theater roof littered the square, along with shattered glass from the windows of nearby cars and restaurants.

The strike hit the theater during a gathering of drone manufacturers and aerial reconnaissance training schools, organizer Mariia Berlinska confirmed. Berlinska said that the event was officially agreed in advance with both the local authorities and the venue. The Chernihiv City Council denied that they had approved the event or issued any permits.

Zelenskyy said the attack showed Russia was a “terrorist state” and that the world must unite against it.

“A Russian missile hit right in the center of the city, in our Chernihiv,” he wrote on Telegram. “A square, the polytechnic university, a theater. An ordinary Saturday, which Russia turned into a day of pain and loss.”

Chernihiv was surrounded by Russian forces at the start of the war but they withdrew after Ukrainian forces retook control of areas north of Kyiv in April last year.

Zelenskyy arrived in Sweden on an unannounced visit Saturday — his first to the Scandinavian country since the start of the full-scale invasion. The war prompted Sweden to abandon its longstanding policy of military nonalignment to support Ukraine with weapons and apply for NATO membership, though it is still waiting to join the alliance.

At a joint news conference, Zelenskyy and Swedish Prime Minister Ulf Kristersson announced the two countries had agreed to cooperate on the production, training and servicing of Swedish CV90 infantry fighting vehicles. Zelenskyy said Ukraine would start manufacturing the vehicles as part of the deal.