A rash of city swarmings - including two separate weekend attacks - are another sign the province's economic boom is not benefiting everyone, says a city criminologist.

"We know there's a segment of middle class that's being wiped out," says Bill Pitt.

"A lot of people are getting rich but a lot of people are not involved in the good times happening in Alberta. There are 4,000 people on the streets who have nowhere to live."

Some of those living on the margins are bent on "making a mockery of the city's law and order," he adds.

Two cases happened yesterday morning and Sunday.

Yesterday, a man was pepper sprayed by three young thugs when he refused to empty his pockets during an attempted robbery. He was walking home near the Dover Hotel on 127 Avenue and 120 Street around 2:15 a.m. when he was approached and surrounded by the culprits, who appeared to be under 18, said police.

About 9:30 p.m. Sunday, two women were swarmed by a gang of men and women at the downtown Grandin LRT Station.

Two men and two women - at least one armed with a knife - demanded one of the victim's cellphones. The other victim contacted police before the group fled.

Police Chief Mike Boyd and Alberta Justice Minister Alison Redford last week warned they will crack down on muggings, swarmings and personal robberies.

Although police have identified downtown as a hotspot for these crimes, Jim Taylor, executive director of the Edmonton Downtown Business Association, said the city centre is still a safe place.

The perception that downtown is dangerous based on statistics can be skewed because the EPS headquarters and the remand centre are both located there, said Taylor.

Numerous assault cases take place inside the jail and the victims and attackers are not members of the general public, he said. Some of the crimes reported to police headquarters didn't take place downtown, he added.

"So you've got to take it a little further and ask, 'What's the nature of the crimes, who's committing them and who are the victims?' " said Taylor.

Sun reader Ron Koyich, who now lives in Hong Kong, sent an e-mail saying he has never before heard of swarming except as it relates to bees.

"Having now finalized our plans for visiting my hometown ... you can perhaps imagine how thrilled I was to read your article and realize we run the risk of being swarmed."

Downtowns of major cities will always have hotspots, Taylor said. But that doesn't mean they are not safe places, he added.