Masked assailants have attacked a Roma camp in western Ukraine, killing one person and injuring four others including a child, police said Sunday.
The incident follows a series of attacks on Roma communities in Ukraine's capital Kiev and in the cities of Lviv and Ternopil that have been condemned by rights groups.
A group of masked individuals attacked the camp on the outskirts of Lviv late on Saturday with weapons including batons, police spokesman Yaroslav Trakalo told AFP by phone.
A 24-year-old man died from stab wounds and four more people were hospitalised, including a 10-year-old Roma boy and a 30-year-old woman, the police spokesman said.
The boy has already been discharged from hospital.
Police said in a statement that they have already detained seven attackers who are aged 16 and 17 and a 20-year-old organiser and found the knife used in the killing.
It is not yet known whether the attackers are members of radical groups.
Police said they opened a criminal case over the "deliberate murder committed by a group of people".
If convicted, the attackers could face up to 15 years in prison.
The head of Ukraine's national police Sergiy Knyazev has said attacks on Roma people by radicals have become more frequent recently, the police statement said.
During an incident in Kiev in April a neo-Nazi group burnt down tents of a Roma community and chased women and small children, throwing stones at them and setting off pepper spray.
Police said they had not opened a criminal probe because none of those attacked in Kiev had reported the crime, Ukrainian media reported.
A neo-Nazi group called C14 posted footage showing its members taking part in the Kiev assault on Facebook and promised more attacks.
In mid-June leading rights groups urged Ukraine to investigate attacks and harassment against the Roma minority, slamming "an atmosphere of near total impunity" in the Western-backed nation.
In a joint letter to Kiev authorities, four groups including Human Rights Watch and Amnesty International condemned what they said was a growing number of attacks by radicals.
"The authorities have so far failed... to respond to most incidents, which has created an atmosphere of near total impunity," the groups said.
The letter said that several radical groups including C14 and Right Sector had been behind at least two dozen attacks or instances of harassment this year.
The Council of Europe rights group estimates the number of Roma in Ukraine at some 260,000, out of a population of around 48.5 million.