Swedish police say school attacker 'had racist motives'

The stabbing attack at a school in western Sweden that left three people dead, including the attacker, is being considered as a hate crime, police said.

"We are convinced that the culprit was driven by racist motives," Police chief Niclas Hallgren told Swedish Radio, citing the selection of victims.

Hallgren said they had also based their conclusion on what was found at the killer's apartment and "his behaviour during the act".

Media reports suggest the 21-year-old attacker had far-right sympathies.

Armed with a sword and wearing a helmet and mask, he stormed a school in Trollhattan, near Gothenburg, before being shot dead by police.

He was seen posing for a photograph with students, who thought he was dressed for Halloween, before going from classroom to classroom at the Kronan School.

A teacher and 17-year-old boy died from stab wounds, while another male student, 15, and 41-year-old teacher remain in serious condition in hospital.

The attack, the first deadly assault on a Swedish school since 1961, has stunned the country which is currently engaged in intense debate over immigration.

The attacker, identified as 21-year-old Anton Lundin Pettersson, was previously unknown to police. Swedish media, after scrutinising his social media accounts, said he had supported a call to stop immigration to Sweden and "liked" pages hailing Adolf Hitler. 

Dressed in black and wearing a mask, Lundin Pettersson knocked on the doors of two classrooms and slashed those who opened them with a sword, authorities said.

Swedish media posted pictures of him posing with students who initially thought he was part of some kind of Halloween prank.

After being called to the scene, officers fired two shots, hitting the attacker with a bullet in the lower chest. He later died in hospital.

"This is a black day for Sweden," Prime Minister Stefan Lofven said of the attack. "It is a tragedy that hits the entire country."

There has been a recent spate of arson attacks on asylum centres in the south of Sweden as the influx of refugees has surged. Immigration officials estimate that about 190,000 will arrive this year, second only to Germany in western Europe.