Ukraine's president Volodymyr Zelensky has vowed to take revenge against Russia after it launched a missile strike on a city that killed seven and wounded more than 100.

Zelensky promised in a video address early on Sunday morning that Ukraine's soldiers would 'respond tangibly' to the strike that hit a theatre and a public square in the northern city of Chernihiv on Saturday.

'Let’s do even more to consolidate the world against Russian terror. Let’s give even more to our state to protect life. Russia must lose this war for life to win,' he starkly added.

The 45-year-old president, speaking at the end of a visit to Sweden, confirmed that 15 children were among the wounded, and also named a six-year-old girl, Sofia, as one of the tragic dead.

Also among the victims were civilians who were celebrating an Orthodox Christian holiday at a nearby church that was damaged, along with a university building.

Volodymyr Zelensky (pictured), speaking at the end of a visit to Sweden, confirmed that 15 children were among the wounded

Also among the victims were civilians who were celebrating an Orthodox Christian holiday at a nearby church

A total of 148 people were wounded in the attack, which has been condemned by the UN as 'heinous'

Zelensky promised in a video address early on Sunday morning that Ukraine's soldiers would 'respond tangibly' to the strike

The governor of the Chernihiv region, Vyacheslav Chaus, revealed that a total of 148 people were wounded in the attack, which has been condemned by the UN as 'heinous.'

The UN's humanitarian coordinator for Ukraine, Denise Brown, said: 'It is heinous to attack the main square of a large city, in the morning, while people are out walking, some going to church to celebrate a religious day for many Ukrainians.'

Ukraine says Russia deliberately targeted the theatre as it was hosting a gathering of drone manufacturers.

The acting mayor of Chernihiv, Oleksandr Lomako, told the BBC: 'I understand that their aim was a military event taking place in the building of the drama theatre and that it was their target.'

He claimed that Russia would've clearly known that the attack would've resulted in civilian casualties.

Ukraine says Russia deliberately targeted the theatre as it was hosting a gathering of drone manufacturers

A local activist said that the theatre meeting was a 'closed meeting of engineers, military and volunteers on the subject of military technologies for the front'

Invitees to the meeting were only given the location a few hours before it started

'It is clear that the Russians launching those missiles and those giving them orders in the middle of the day to the civilian city realised that the victims will be primarily civilians.

"There is no other way to interpret it than a war crime against civilians, yet another Russian war crime," he added.

A local activist, Maria Berlinska, said in a Facebook post that the theatre meeting was a 'closed meeting of engineers, military and volunteers on the subject of military technologies for the front.'

She said that while the event was relatively public, invitees were only given the location a few hours before it started.

Maria said that the organisers are now working with Ukraine's security service, the SBU, to figure out how Russia knew about the meeting.

The pledge comes on the same weekend that the Netherlands and Denmark announced that they were gifting Ukraine several F-16 fighter jets.

The exact timeline for the jets' use will depend on how quickly Ukrainian crews and infrastructure can get ready, Dutch Prime Minister Mark Rutte told Zelensky as the two visited a Dutch air base.

The pledge comes on the same weekend that the Netherlands and Denmark announced that they were gifting Ukraine several F-16 fighter jets

The exact timeline for the jets' use will depend on how quickly Ukrainian crews and infrastructure can get ready

Ukraine has long pleaded for the sophisticated fighter to give it a combat edge

Zelensky declined to say how many Ukrainian pilots would undergo training in Denmark and later in Romania, citing security reasons

Officials have previously said that Ukrainian pilots will need six to eight months of training

On Friday, the Netherlands and Denmark said the US had authorised them to deliver American-made F-16s to Ukraine

Ukraine has long pleaded for the sophisticated fighter to give it a combat edge.

Ukraine's president welcomed the 'historic' announcement and praised Mr Rutte for making the Netherlands the first country to offer the planes.

'It makes me proud that Denmark, together with the Netherlands, will donate F-16 fighter jets to Ukraine's fight for freedom against Russia and its senseless aggression. Denmark's support for Ukraine is unwavering, and with the donation of F-16 aircraft, Denmark is now leading the way,' Danish Defence Minister Jakob Ellemann-Jensen said in a statement.

Zelensky called the announcement a powerful message to his forces.

'F-16 will certainly give new energy, confidence, and motivation to fighters and civilians. I'm sure it will deliver new results for Ukraine and the entire Europe,' he said.

Zelensky declined to say how many Ukrainian pilots would undergo training in Denmark and later in Romania, citing security reasons.

However, Denmark said on Friday that the training is starting this month.

Officials have previously said that Ukrainian pilots will need six to eight months of training.

On Friday, the Netherlands and Denmark said the US had authorised them to deliver American-made F-16s to Ukraine.

Washington says the F-16s - like the advanced US Abrams tanks - will be crucial in the long term as Kyiv faces down Russia.

Ukraine has been relying on older aircraft, such as Russian-made MiG29 and Sukhoi jets. F-16s have newer technology and targeting capabilities. They are also more versatile, experts say.