Police on Monday detained suspects after a 3-year-old boy was shot dead in a car in Kiev in an attack targeting his father, a businessman and regional lawmaker.
The attacker aimed at the car driver, but the bullet hit the boy who was also inside, Kiev police said after the city centre shooting on Sunday evening.
"The child died from a gunshot wound in the ambulance on the way to the hospital," police said. His father was not injured.
Police said the motive for the attack was the father's business activities and they were still seeking the mastermind after detaining two teenage shooters and finding the murder weapon.
The target was identified as Vyacheslav Sobolyev, a restaurant owner and Kiev regional lawmaker who represents the party of ex-president Petro Poroshenko.
The shooting took place outside an Italian restaurant he owns.
Ukraine's police chief told reporters they had detained two suspects aged 18 and 19 armed with a rifle.
"(They) fired from a neighbouring house," Igor Klymenko, the head of Ukraine police, said at a news conference.
Kiev police chief Andriy Kryshchenko said the "reason for this fatal shot was the father's business and economic activity.
"Nothing will stop the police from finding the masterminds of this crime," he added.