Several masked men stormed a theatre in Stockholm that was hosting an anti-fascist event and set off smoke bombs that injured several attendees, according to Swedish police.
"A group of Nazis" came into the theatre just before the event was scheduled to start late Wednesday and attacked visitors and threw smoke grenades into the hall, according to the anti-racist foundation and watchdog, Expo.
At least 50 people attended the event which was organized by the Left Party and Green Party at the Gubbangen theatre in a southern suburb of Stockholm.
"The Nazis attacked visitors using physical violence… vandalised the premises before throwing a type of smoke bomb that filled the entrance hall with smoke," Expo wrote on its website.
Several people were taken to hospital by ambulance for checks after inhaling smoke as the rescue service and the police rushed to the scene.
"Three people were taken by ambulance to hospital," said a police statement.
The attack was condemned by all political parties, including Prime Minister Ulf Kristersson.
"It's terrible that a meeting organised by the left-wing party has been attacked," Kristersson, was quoted by the TT news agency.
The prime minister called it an attack on Sweden's democracy, adding that the incident had no place in the country, it said.
"This type of hateful behaviour has no place in our free and open society.
"An attack on a democratic meeting is an attack on our entire democracy," he said.
No arrests have been made, however, police spokesperson Ola Osterling told national broadcaster SVT that an investigation is going well and officials have very good footage.
Earlier this month another group of masked men from the Nazi Nordic Resistance Movement (NMR) attacked an EU migrant camp in northern Stockholm.
NMR took responsibility for the attack in a video published by the group.
The Nazi group has written about the attack and published pictures and a video in which they are seen tearing down the camp calling it a "clean-up operation."
