(NewsNation Now) — Russia launched a wide-ranging attack on Ukraine in the early hours of Thursday, hitting key cities and military bases with airstrikes or shelling, causing 100,000 civilians to flee by trains and cars.

Russian military advanced from three sides Thursday — north from Crimea, south from Belarus and west from the Donetsk and Luhansk separatist regions — leading some to suggest the ultimate goal is to encircle the capital of Kyiv.

President Vladimir Putin ignored global condemnation and cascading new sanctions as he unleashed the largest ground war in Europe in decades, and chillingly referred to his country’s nuclear arsenal. He threatened any country trying to interfere with “consequences you have never seen.”

Some of the most intense fighting was outside of Kharkiv in the northeast, according to The New York Times. Russian forces have used more than 100 medium- and short-range ballistic missiles to strike Ukrainian military installations and air-defense targets, the Times reports, citing a senior defense official.

Simultaneously, Russia launched cyberattacks on Ukraine’s Parliament, banks and government offices. Experts say it is possible this online attack was planned months ago — but was timed to coincide with an invasion. 

At least 137 Ukrainians have been killed so far in the invasion and 316 have been wounded, according to Ukrainian President Volodymyr Zelensky.

In a video address released early Friday, Zelensky called them “heroes.”

Zelensky says that despite Russia’s claim it is attacking only military targets, civilian sites also have been struck. In his words: “They’re killing people and turning peaceful cities into military targets. It’s foul and will never be forgiven.”

Report: Heavy explosions heArd in Kyiv

Heavy explosions were heard in Ukraine’s capital early Friday, according to a Reuters witness. The witness said the blasts were a series of sounds similar to artillery fire.

The Minister of Foreign Affairs of Ukraine Dmytro Kuleba confirmed the news.

“Horrific Russian rocket strikes on Kyiv. Last time our capital experienced anything like this was in 1941 when it was attacked by Nazi Germany. Ukraine defeated that evil and will defeat this one. Stop Putin. Isolate Russia. Severe [sic] all ties. Kick Russia out of everywhere.”

Minister of Foreign Affairs of Ukraine Dmytro Kuleba

Ukrainian males aged 18-60 are banned from leaving the country, Zelensky says 

According to the AP, Male Ukrainian citizens aged 18 to 60 have been prohibited from leaving the country while martial law is in place.

In a statement posted on Facebook, the State Border Guard Service of Ukraine said “departure from Ukraine is restricted” temporarily.

“It is forbidden to travel outside the borders of Ukraine [for] citizens of Ukraine, male gender between 18 to 60 years old,” the statement said.

Russian sabotage groups enter Kyiv

President Volodymyr Zelensky said “enemy sabotage groups” have entered Kyiv, the Ukrainian capital.

Zelensky, in a video statement Thursday, said “the enemy’s sabotage groups have entered Kyiv.” He also urged residents to be vigilant and to abide by the curfew rules.

His own family is hiding out due to threats on their lives, he said.

“The enemy has identified me as target No. 1 and my family as target No. 2. They want to destroy Ukraine politically by destroying the head of state,” Zelensky said.

Hostomel airport recaptured

Ukrainian National Guard units have recaptured the Antonov International Airport in Hostomel, after an attack by Russian assault helicopters and jet fighters, according to the Ministry of Internal Affairs’ website.

Videos shared on Twitter show Russian Ka-52 and Mi8 helicopters descending on the strategic military airfield.

Attacks have also been reported in 18 other Ukrainian cities, including Pripyat, Hlukhiv, Konotop, Kharkiv, Nova Kakhovka, Henichensk, Zmiinyi Island and Mariupol, Bloomberg reports.

Chernobyl nuclear plant taken by Russia

Among the most worrying developments on an already shocking day, Russian troops captured the Chernobyl nuclear plant, Ukrainian officials said. Radioactivity is still leaking from the scene of the world’s worst nuclear disaster, which took place in 1986.

Ukrainian officials said their forces were battling Russians on multiple fronts, and the condition of the plant’s facilities, a confinement shelter and a repository for nuclear waste is unknown.

The nuclear plant is located less than 100 miles north of Ukraine’s capital, Kyiv.

An official familiar with the situation told The Associated Press that Russian shelling hit a radioactive waste repository at Chernobyl, and an increase in radiation levels was reported. The increase could not be immediately corroborated.

The International Atomic Energy Agency said it is following the situation in Ukraine “with grave concern” and appealed for maximum restraint to avoid any action that may put Ukraine’s nuclear facilities at risk.

This is a developing story. Please check back for updates.