An Afghan migrant has been shot dead by a Bulgarian border guard after entering the country from Turkey.
The man - who was among a group of about 50 people said to be from Afghanistan - was shot near the town of Sredets in south-eastern Bulgaria.
Officials say he was killed by the ricochet of a bullet fired as a warning to the migrants.
The UN's refugee agency says that the incident is the first of its kind in the migrant crisis.
UNHCR spokesman Boris Cheshirkov said the agency was "deeply shocked" by the incident and called on the Bulgarian authorities to commission an independent investigation into the death.
Bulgarian Prime Minister Boyko Borisov left the EU migration talks on hearing reports of violence at the border.
"Our border patrol of border guards and police in the area stumbled on 50 offenders, who illegally entered the country," Bulgarian interior ministry official Georgi Kostov told national radio.
He said a warning shot was fired after the migrants resisted arrest.
The surviving migrants - aged between 20 and 30 - have been detained, he said.