STOCKHOLM, June 19 (Xinhua) -- Three people were shot dead and three others wounded in Malmo, southern Sweden on Monday evening in a shooting that has been described as one of the worst Sweden has experienced in decades.

According to Malmo police, all six victims were members of criminal gangs and involved in serious crime in Malmo. The dead are 19, 27 and 29 years old, Swedish Radio reported on Tuesday.

"It is unusual for so many people to be shot in a single incident," Mikael Rying, a criminologist at the Swedish police's department of National Operations (NOA) told Swedish Television.

"There are other examples of cases with three victims, but they are rare. It seems like they shot into a crowd of people," Rying added.

The shooting took place outside an Internet cafe at around 8 p.m. local time on Monday evening and there are conflicting accounts of exactly what happened, with early reports of a drive-by shooting.

Gun violence is a growing phenomenon in Sweden, where there were 320 shooting incidents last year, most of them in the Stockholm region, as well as in the other main cities, Gothenburg and Malmo. A total 43 people were killed and 140 were wounded, according to Swedish Television.

"The violence tends to culminate and then calm sets in when the police have arrested enough people or when enough people have been shot," he said.

At the same time, it is more and more common for the deadly violence to take place in the open, thereby endangering members of the public as opposed to just gang members.

"The shooting in Malmo happened in a central location, on a busy street where many people move about. It is serious that they are shooting on open streets," said Rying.