By Stefan J. Bos
Ukrainian police say a masked group armed with batons and other weapons targeted the camp of Roma overnight on the outskirts of the western city of Lviv.
A 24-year-old man reportedly died of stab wounds, while four others - including a 10-year-old boy - were injured.
Authorities have confirmed that seven people were detained.
It is the latest in a series of attacks on Ukraine's embattled Roma community.
In April, the far-right group C14 burnt down tents in a Roma camp in the capital Kiev and chased women and children.
In a joint letter earlier this month, human rights groups including Amnesty International and Human Rights Watch warned against the increase in attacks by far-right groups on minorities in Ukraine.
However Gypsies, who prefer to be known as Roma, are the most impoverished and discriminated group in Ukraine and neighboring countries.
Rights activists say that authorities have "failed" to respond to most incidents, leading to "an atmosphere of near total impunity that they claim cannot but embolden extremists to commit more attacks".
The last Ukrainian census in 2001 estimated the Roma population to be around 40,000, but rights groups say the figure could be as high as 260,000.
The latest violence adds to instability in the former Soviet nation which is still facing an ongoing conflict between pro-Russian separatists and Ukrainian forces in the east.
That conflict has killed more than 10,000 people, including children.