STOCKHOLM - Two men were killed and more than 10 were wounded after gunmen burst into a pub firing automatic weapons in a suspected gang-related attack in the Swedish city of Gothenburg late Wednesday.

Customers in the bar were watching football on television when at least two gunmen, reportedly wearing skeleton masks and yellow high visibility vests, launched their shooting spree.

“We are assuming that this is gang-related and not a terrorist attack,” police spokesman Bjoer Blixter told AFP. “We’ve had similar problems with shootings for several years but never of this magnitude.” A manhunt is under way for the assailants who fled by car after the shooting in a predominantly immigrant area of Sweden’s second city. Gothenburg police said they have launched a murder investigation and are questioning a large number of people but no arrests have been made.

“They aimed directly at people... at their heads,” a pub employee told the Aftonbladet tabloid of the attack.

Blixter said two people in their 20s died and between 10 and 15 others were wounded, but the death toll could rise. The injured were aged between 20 and 60.

Sahlgrenska University Hospital said it was treating eight people, including one with life-threatening injuries and two in serious but stable condition.

Sweden and neighbouring Denmark have a longstanding problem with criminal gangs, including Hells Angels, Bandidos and several immigrant groups which battle for control of the local drugs trade and protection rackets.

The shooting fitted a pattern of regular tit-for-tat retributions between rival gangs in areas with high immigrant populations in Gothenburg, which lies on Sweden’s southwestern coast and has a population of 550,000.

Regional police chief Klas Friberg said officers had been “on their toes” lately because of an uptick in reports of gang clashes.

“We have different types of criminal gangs which are prepared to... use extreme violence in revenge attacks or to increase their share of the criminal market,” he told reporters.

“It’s a difficult situation... There are about 100 men in various gangs who are always prepared to use violence and commit crimes - who have crime on their minds 24 hours a day, 7 days a week.”

One witness told Aftonbladet that two people entered the pub in the suburb of Biskopsgaarden armed with weapons that looked like Kalashnikovs and started shooting.

Another witness said the attack was over quickly.

“I didn’t have time to think what was happening. Then I saw that my friend was bleeding. I tried to stop the flow of blood as well as I could with my hands,” a man who gave his name as “Rocky” told public broadcaster SVT.

There have been dozens of gang-related shootings in Gothenburg in recent years, many of them in the Biskopsgaarden area, a housing estate with a large immigrant population and high unemployment, but fatalities are relatively rare.

According to local tabloid GP, there were a total of 52 shootings in Gothenburg last year, of which four were fatal. In the past 18 months, police said they had seized almost 200 weapons, including 50 automatic weapons as part of an anti-gang operation.

In 2010, Biskopsgaarden became one of the first areas in Sweden to mount video surveillance cameras in public places because of the high level of crime in the neighbourhood of 12,000 people, according to the municipality.

In some areas of Biskopsgaarden, 80 percent of inhabitants are of immigrant origin.

A man was shot dead in an apartment in the area in May last year and two others died in suspected gang-related shootings during an upsurge in violence in late 2013.

In January a man was shot in the leg close to the scene of Wednesday’s shooting.

“It’s frightening. Things happen nearly every day here but this looks like something extra,” one local resident who did not give her name told Aftonbladet.

However another resident said the area around the pub was usually quiet.

“This is actually a quiet area... there have been occasional shootings but never anything serious. It’s all between gangs,” she said.

Sweden, which has a population of 9.5 million, is generally a tranquil country and gun-related deaths are uncommon.

In 2013, a total of 87 violent deaths were reported, including 26 gunshot fatalities, according to the Swedish National Council for Crime Prevention.