Shock images from Russian invasion of Ukraine

Refugees are fleeing for their lives and anti-war protesters are clashing with Russian police as air strikes rain down on Ukrainian cities. Warning: GRAPHIC CONTENT

Hundreds are feared dead and countless more injured as Russian tanks, helicopters and troops swept across the border of Ukraine.

NATO activated its response force, placing 120 ships, 100 aircraft, and 40,000 troops on alert.

Russian ally Belarus threatened to deploy Iskander and S-400 missile defence systems as Vladimir Putin’s so-called “special military operation” threatened to spill out into a larger conflict across Europe.

Explosions were heard in the capital city of Kyiv and in faraway cities Kharkiv, Kramatorsk, Mariupol.

Russians troops reportedly disguised as Ukrainian police and tanks bearing the white insignia of “observers” rolled in from Belarus, Russia and Crimea.

An Ukrainian mother cries after crossing to Poland to seek asylum. Picture: Dominika Zarzycka/NurPhoto

People speak to officials at Romania’s border with Ukraine in Sighetu Marmatiei. Picture: Andreea Campeanu/Getty Images

Ukrainian families are seeking refuge in neighbouring Romania. Picture: Andreea Campeanu/Getty Images

In Saint Petersburg, Russia, police officers are detaining anti-war protesters. Picture: Valya Egorshin/NurPhoto via Getty Images

Protests have broken out around the world. Here, a pro-Russian and a pro-Ukrainian demonstrator clash outside the Russian Embassy in Tallinn, Estonia. Picture: Raigo Pajula / AFP

Air raid sirens rang out across the country as subway stations were flooded with Ukrainians fleeing the incoming attack.

Martial law was declared as Ukrainians made a run on currency exchanges and petrol stations amid the panic to move west away from the conflict.

There was traffic chaos as more fled by car, causing long queues along motorways away from the major hot spots.

Ukrainian defence officials later said that Kiev's main international airport had come under a Russian bombing attack.

At least seven military helicopters were captured on video flying to the Ukraine air base of Gostomel, northwest Kyiv. Ukraine authorities said at least three of the choppers were downed in the Russian attack.

A wounded woman stands outside a hospital after the bombing of the eastern Ukraine town of Chuguiv. Picture: AFP

The Ukrainian State Border Guard Service site has been damaged by shelling in Kyiv region Picture: Press service of the Ukrainian State Border Guard Service/Handout via Reuters

Ukrainian servicemen stand near an armored personnel carrier BTR-3 on the northwest of Kyiv. Picture: AFP

Ukrainian servicemen get ready to repel an attack in Ukraine's Lugansk region. Picture: AFP

A Ukrainian military plane with 14 people aboard crashed south of Kyiv. Emergency services said they were still determining how many people died. Picture: AFP

The body of a rocket in a flat on the northern outskirts of Kharkiv. Picture: AFP

Military personnel throw items into a fire outside an intelligence building as Russia began its large-scale attack. Picture: Getty

Firefighters tackle a fire after bombings in the eastern Ukraine town of Chuguiv. Picture: AFP

People withdraw money at a cash dispenser in Kyiv as air raid sirens rang out. Picture: AFP

People carrying bags and suitcases escape Kyiv via the metro as explosions ring out across the city. Picture: AFP

Russian helicopters in attack formation over Gostomel Airport, northwest of Ukraine’s capital. Picture: Supplied

Smoke rising near the town of Hostomel and the Antonov Airport, in northwest Kyiv, where Russian and Ukrainian forces battled for control of an air base. Picture: AFP

People hug as a woman with a suitcase passes by outside a metro station in Kyiv on the morning of the invasion. Picture: AFP

Ukrainian servicemen get ready to repel an attack in Ukraine's Lugansk region as Russia invades. Picture: AFP

A man uses a carpet to cover a body stretched out on the ground after bombings on the eastern Ukraine town of Chuguiv. Picture: AFP

Black smoke rises from a military airport in Chuguyev near Kharkiv as Russian and Ukrainian forces battle for control of the air. Picture: AFP

People walk past the body of a relative outside a destroyed building after bombings on the eastern Ukraine town of Chuguiv. Picture: AFP

A woman holds a cross as she prays at Independence Square in Kyiv on the morning of Russia’s invasion. Picture: AFP

US Air Force F-35 Lightning II aircraft prepare to land at the 86th Air Base, Romania. Picture: AFP

Ukrainian military vehicles move past Independence Square in central Kyiv as Russia invades. Picture: AFP

Cars sit at a standstill as people try to leave Kyiv. Picture: Getty Images