Ukrainian schoolchildren head underground in bomb-proof classrooms as Vladimir Putin launches latest onslaught on the city of Kharkiv

Holding hands under the watchful eye of their teacher, frightened Ukrainian children are ushered into a bomb-proof bunker yesterday as Vladimir Putin launches his latest onslaught on their city. 

With the Kremlin's so-called 'second invasion' of Ukraine gathering pace, pupils at a school in Kharkiv went underground for respite. 

The major city, where more than a million Ukrainians are once again in fear for their lives, has not been seriously threatened for two years. 

Back in early 2022, against all odds, the Russian invaders were repelled after bombarding it with rockets and even banned cluster munitions.

As the pupils were led down into the air-tight and windowless makeshift school, those closer to the frontline were fleeing the fighting. 

Holding hands under the watchful eye of their teacher, frightened Ukrainian children are ushered into a bomb-proof bunker

With the Kremlin's so-called 'second invasion' of Ukraine gathering pace, pupils at a school in Kharkiv went underground for respite

Students in a lesson that is being conducted in one of the air-tight and windowless makeshift classrooms

Vovchansk stands around 45 miles north-east of Kharkiv and was yesterday in the sights of Vladimir Putin's forces. 

As the Russian army advanced, thousands of men, women and children left the town. 

Only an estimated 2,500 of its 17,000 residents remained yesterday as the fighting intensified and, despite their valiant efforts, out-gunned Ukrainian troops were forced to withdraw. 

The speed of Russia's advance has been blamed on poorly built fortifications around Vovchansk and enduring issues surrounding a lack of ammunition and weaponry.

Younger students in a lesson taking place in the underground bunker whilst their town is under attack

A teacher continues to teach her students in the classroom bunker despite Putin's latest attack taking place above them

Mass civilian evacuations of border towns in Ukraine's northeastern Kharkiv region are underway amid heavy Russian shelling and troop movements. A destroyed house is pictured following shelling on May 12, 2024 in Vovchansk

A fire spreads through a forest following shelling on the outskirts of Vovchansk, Kharkiv region, northeastern Ukraine, 12 May 2024

Frustrated Ukrainian troops suggested the Russians had been able to simply 'walk in'.

Local officials fear Vovchansk could become the next Bakhmut – the city devastated last year by Russian scorched earth tactics. 

Ever since Kharkiv – Ukraine's second city – repelled an assault in early 2022, it has stood as a beacon of resistance. 

But Russia is once again on the march and its troops are better equipped and more tactically adept. 

The intensity of the attacks has appeared to take Ukrainian commanders and their Western advisers by surprise after months of little movement on the 620-mile frontline.