Image source, State Emergency Service of Ukraine

At least 21 people have been killed and 83 more injured, including seven children, Ukraine's Interior Minister, Ihor Klymenko, and the state emergency service say in an update on their Telegram channel.

The death toll is according to "preliminary data", they say, and that people were injured "in the middle of the street, in cars, public transport, in houses".

The emergency service says they are deploying "headquarters" to provide assistance to the victims and that psychologists will work with the victims.

"Investigators and forensic experts are at the scene of the attacks - collecting evidence, documenting the brutal war crime of the Russian Federation against the civilian population," the service adds.

James Waterhouse
Ukraine correspondent in Kyiv

This appears to be a direct hit on a bustling city on a Sunday morning. An explosion was captured on one driver’s dashcam in a major street.

There are also scenes of devastation, with burning vehicles, bent trees, and the occasional colour of a dead person’s jacket.

In Sumy, the death toll will only rise in a place now habitually pummelled by Russian forces across the nearby border.

It’s a part of Ukraine where Russian forces are thought to be preparing for a major offensive, as they continue to pursue their goal of occupying as much of the country as possible.

We can bring you more from Ukraine’s President Volodymyr Zelensky who describes the Russian missile strike on Sumy that hit “an ordinary city street, ordinary life” as “horrific”.

He says early reports suggest dozens of civilians have been killed or injured before adding: “The world must respond firmly."

“What’s needed is an attitude toward Russia that a terrorist deserves," he says.

Posting on his Telegram channel, President Zelensky says Russia hit the centre of Sumy "on the day when people go to church – Palm Sunday, the feast of the Lord's Entry into Jerusalem".

"The United States, Europe, everyone in the world who wants an end to this war and murders. Russia wants exactly this kind of terror and is dragging out this war. Without pressure on the aggressor, peace is impossible," Zelensky says.

He adds that "talks have never stopped ballistic missiles and air bombs".

More than 20 people have been killed after a "missile strike on civilians" according to the acting mayor of Sumy, Artem Kobzar.

Ukrainian President Volodymyr Zelensky says the "terrible strike by Russian ballistic missiles" hit "an ordinary city street, ordinary life: houses, educational institutions, cars on the street" and that a rescue operation is now under way.

The president calls for a "a tough reaction from the world".