(CNN) Russia launched an invasion of Ukraine on Thursday, sending troops into the ex-Soviet nation from three fronts and firing missiles on several locations near the capital, Kyiv, in a broad attack that has drawn deep condemnation from world leaders.
At dawn, troops and armor crossed into eastern Ukraine from the Russian border, as well as from Belarus in the north and from Russia-annexed Crimea to the south.
Here's how it unfolded.
3:59 a.m. (8:59 p.m. ET, Wednesday): Livestream video from a border crossing station between Crimea -- which was annexed by Russia in 2014 -- and parts of southern Ukraine viewed by CNN showed what may have been the first signs of the Russian invasion.
In the video, a guard at the Kalanchak crossing is seen reacting to something heading towards the Ukrainian border. The guard begins moving back towards the gate, and soon another guard comes into frame.
About 25 seconds later, people who had just walked across to Crimea, are seen -- suitcases in tow -- running back across the border. The lights suddenly go out at the station, and the camera switches to black and white, recording in infrared.
4:08 a.m.: An individual dressed in camouflage is seen carrying a flashlight coming around one of the border guard stations. Three minutes later, three more individuals in camouflage are seen walking around the border crossing. Minutes later, the the camera cuts out.
Very soon after, another webcam at the Chongar border crossing -- the only other active border crossing station from Crimea -- shows lights suddenly turning off, and, minutes later, the camera turns off as well.
4:50 a.m.: Russian President Vladimir Putin made a speech, saying he had decided "to conduct a special military operation ... to protect people who have been subjected to abuse and genocide by the Kyiv regime for eight years," repeating a baseless claim about Ukraine's Russian-separatist-backed Donbas region.
He denied, however, that Russia was planning to occupy Ukrainian territories. "We are not going to impose anything on anyone by force."
He went on to warn: "Whoever tries to interfere with us, and even more so, to create threats for our country, for our people should know that Russia's response will be immediate and will lead you to such consequences that you have never experienced in your history."
5.07 a.m.: Russian forces launched a series of missile attacks against locations near Kyiv, as well as the use of long-range artillery against the northeastern city of Kharkiv, near the Russian border.
Before daylight: The strikes quickly spread across central and eastern Ukraine, as Russian forces attacked the country from three sides. People in the cities of Odessa, Dnipro, Mariupol and Kramatorsk reported huge blasts.
Several detonations to the east of Kyiv let off massive plumes of gray smoke rising into the night sky. One of the chief targets was the main international airport at Boryspil, which is pummeled by missiles.
Video showed a cruise missile hitting a military installation at the airport at Ivano-Frankivsk in western Ukraine. Airports were also hit in Kharkiv, Ozerne, Kulbakino, Chuhuiv, Kramatorsk and Chornobaivka.
Most of the targets were military bases, but there was clearly substantial damage in and around several cities. In Kharkiv, video emerged of an apartment block that had been damaged by a missile or long-range artillery. Another video showed a rocket embedded in a road. The State Emergency Service reported that six people were trapped in rubble in Nizhyn.
Ukraine's interior ministry said ballistic missiles had been used as part of the offensive, while jets were heard over the central city of Zaporizhzhye.
The Russians used a wide array of weaponry in their assault, including attack aircraft and helicopters, tanks, long range artillery and missiles.
6.48 a.m.: Ukrainian President Volodymyr Zelensky responded to Putin with a minute-long speech of his own, saying he had spoken to US President Joe Biden and that the US was rallying international support for Ukraine.
"The West is with us," he said, and announced martial law across the country.
At the same time, a livestream video seen by CNN showed troops atop a column of military vehicles entering Ukraine from a border crossing with Belarus. The livestream video was taken at the Senkivka, Urkaine crossing with Veselovka, Belarus.
7 a.m.: After dawn, air raid sirens sounded across Kyiv and at around 7:45 a.m., sirens go off in the western city of Lviv.
A short time later, a single, unidentifiable plane roared above the capital.
8.00 a.m.: Ukraine claimed it had shot down five Russian aircraft and a helicopter. Russia denied losing any aircraft.
As the day began in Kyiv, streams of vehicles could be seen crossing the North Bridge, heading west, away from the focus of the Russian assault. Other people in the capital sought shelter in subway stations.
Across the country, long lines formed at gas stations and cash machines. A few people gathered in the streets of Kharkiv to pray.
An eyewitness who saw and heard the latest strike in the town of Brovary on the outskirts of Kyiv described the situation as "terrifying."
11.28 a.m: Ukrainian leader Zelensky made a televised address, in which he said Russia has attacked Ukraine in a "cunning way," comparing him to Hitler in World War II.
He called on "everyone who is able" to join the military and called on veterans to come forward.
"From today our countries are on opposing sides of world history. Russia is on the side of evil, but it depends on the Russian people," he said.
"The people of Russia will have to choose which path each of them takes. Everyone in Russia who has not lost their honor, they have time to come out and protest this war."
12:37 p.m.: More than 40 soldiers and about 10 civilians had been killed, Ukrainian authorities said.
12:45 p.m.: CNN teams in Kyiv, Kharkiv, Odessa and Mariupol heard more strikes, though they appear to be less severe than explosions reported earlier.
12:55 p.m.: Around five blasts were heard by a CNN team in Kharkiv, Ukraine's second-largest city.
Around 2 p.m.: A K-52 "Alligator" Russian helicopter was shot down in the Kyiv region, near Mezhyhirya, the Ukrainian Interior Ministry confirmed.
All timings are in local Ukrainian time and are estimates.