Sweden's prime minister has described as a "terrible crime" the stabbing of a 22-year-old female employee at a centre for young asylum seekers.
Prime Minister Stefan Lofven visited the centre for unaccompanied migrants in Molndal, near Gothenburg, hours after the killing.
An asylum seeker of 15 was arrested on suspicion of murder. The victim has been named locally as Alexandra Mezher.
Mr Lofven said many Swedes feared that such attacks could happen again.
"I believe that there are quite many people in Sweden who feel a lot of concern that there can be more cases of this kind, when Sweden receives so many children and youth, who come alone [to seek asylum]" he was quoted as saying by Radio Sweden.
Police officers arriving at the scene at Molndal near Gothenburg found a "crime scene with a lot of blood", said spokesman Thomas Fuxborg.
"The perpetrator had been overpowered by other residents, people were down and upset."
The victim, whose family was described as Lebanese in origin, died in hospital of her injuries.
Ms Mezher had worked at the asylum centre for a few months and a cousin quoted by Expressen newspaper said she was "an angel who wanted to do good". She had been planning to do a postgraduate course in social sciences, Goteborgs-Posten reported.
A knife believed to be the one used in the attack was recovered.
The residents at the home, all aged between 14 and 17 and about 10 in number, were moved to new accommodation for the night, according to local media.
Pressure on police
Sweden's National Police Commissioner, Dan Eliasson, has requested 4,100 additional officers and support staff to help fight against terrorism, carry out migrant deportations and police asylum facilities, Swedish news agency TT reports.
"We are forced to respond to many disturbances in asylum reception centres," he was quoted as saying.
"In some places, this takes significant police resources. This was not the case six months ago and it means that we won't be able to respond as effectively in other areas."
Sweden accepted almost 163,000 asylum applications last year, almost a third of them from Syria. Migration officials say 35,400 unaccompanied minors sought asylum in Sweden in 2015, five times the number in 2014.
The national migration agency has described the surge in arrivals from unaccompanied minors as "a great challenge for all municipalities in the country".
Along with Germany, it is a prime destination for refugees and other migrants entering the EU illegally.
However, it recently introduced temporary border checks in a bid to control the influx of people.