A car bomb in central Kiev on Wednesday morning killed well-known pro-Western journalist Pavel Sheremet, with the crisis-hit nation's president demanding the perpetrators are brought to justice.
The 44-year-old, originally from Belarus but a Russian citizen who worked for Ukrainska Pravda, an independent news site, died when an explosion tore through the car he was in.
The charred car with all the doors open stood on the cobbled street behind a police cordon as investigators worked at the scene, AFP journalists at the scene said.
"Pavel Sheremet's death is the result of an explosive device. It's murder," said Prosecutor-General Yuriy Lutsenko on Facebook.
President Petro Poroshenko described his death as a "crime" and a "terrible tragedy," saying that "the guilty must be punished."
The interior ministry called Sheremet's killing a "brazen murder" aimed at destabilising the country.
An aide to the interior minister Zoryan Shkiryak said on Facebook that the explosive device was believed to be the equivalent of 400 to 600 grams of TNT, possibly set off remotely or on a timer.
"All possible scenarios of this cruel crime are being looked into," Shkiryak said, adding that explosives experts were working at the scene.
A taxi driver who gave his name only as Petro, told AFP that Sheremet "was driving along Ivana Franka street and stopped at the turn and then an explosion went off. The flames from the windscreen went up to the second floor."
"We rushed to the car and opened the door, he was lying on the floor and groaning. He was in shock from pain and his legs seemed to be broken," the driver said.
He said that witnesses called for an ambulance and started dragging him out because the car was burning more and more strongly. Sheremet was unable to speak but was moaning from pain. When the amubulance came, he was still alive.
The car he was driving was not his own but belonged to the founding editor at Ukrainska Pravda, Olena Prytula, the news outlet reported.
- 'Destabilise the situation' - Sheremet had worked for several years at Ukrainska Pravda, whose founder Georgiy Gongadze was murdered in 2000 after opposing then-president Leonid Kuchma.
Gongadze's killing was a national scandal, but while those alleged to have carried out the hit were jailed no one has yet been charged with giving the order for his murder.
The editor of Ukrainska Pravda Sevgil Musaieva-Borovyk told AFP he thought Sheremet was killed for his "professional activity."
"Why do they kill journalists in Ukraine? Someone wants to destabilise the situation in the country by doing this," the editor said.
Sheremet also worked on a radio station Vesti, where he was due to host a show after leaving home Wednesday morning. The station is criticised by some Ukrainians as being too pro-Russian.
Sheremet was born in Belarus and in television there before leaving due to a conflict with the repressive regime of Alexander Lukashenko. He founded the popular Belarussky Partizan opposition news website.
He then worked for Russia's ORT television network and at one point was anchor on the country's most watched news show Vremya, or Time.
He later worked for Russia's state Obshestvennoye Televideniye, or Public Television, a channel set up in 2013, but resigned in 2014 in protest at Russia's stance towards Ukraine in covering the upheaval in the country.
Dunja Mijatovic, OSCE Representative on Freedom of the Media, wrote on Twitter that Sheremet's murder was "devastating news," calling for the perpetrators and masterminds to be brought to justice.
The killing comes as Ukraine is continuing to battle separatists in its east and is still struggling to reach stability amid political infighting and an economic collapse.
The separatist conflict in the east that Kiev and its Western allies accuse Russia of plotting and backing is now in its third year and has killed 9,500 people.