Thousands of shoppers attended the opening of CrossIron Mills mall in Balzac, north of Calgary, on Wednesday. (Zulekha Nathoo/CBC)

More than 20,000 people had filed into the CrossIron Mills by noon on the opening day of the mega-mall north of Calgary.

The mall – one million square feet with space for 200 stores – opened its doors at 10 a.m. Wednesday in Balzac, but some shoppers began to line up outside the building as early as 5 a.m. to take advantage of special deals.

"I'm definitely supposed to be working but did take the day off. I've been looking forward to the mall opening," said shopper Cory Smillie.

Despite concerns about traffic tie-ups and extra RCMP officers on duty around the mall, police reported five minor collisions that did not result in any injuries.

The RCMP are investigating an incident in which a female driver trying to park in a stall at the mall brushed up against a pedestrian trying to hold that space for another vehicle.

Police also detained two men in a vehicle who pointed what ended up being a plastic replica gun at another vehicle entering the mall area.

Mall management expected about 70,000 shoppers on Wednesday and 30,000 cars using Highway 2 and the single exit ramp.

Some people started lining up as early as 5 a.m. for the mall's opening at 9:30 a.m. (CBC)

"That's manageable with a lot of patience and a lot of work … but people will get in there," said RCMP Sgt. Patrick Webb.

CrossIron Mills is the first indoor shopping centre to open in Alberta in 20 years.

Many of the stores open on Wednesday were familiar chain businesses but in a larger format.

"It's a nice change from the other malls," said shopper Melissa Quon.

Early in its construction, developers struggled to get a water licence, and some question the economic feasibility of opening a mega-mall during an economic downturn.

But John Scott, vice-president of development for Ivanhoe Cambridge, said the company responsible for the $495-million project isn't worried.

"We're looking at it in terms of the value component here. With 55 per cent outlet [stores], people are going to seek that out there's no question," he said on Wednesday.

Shopper Bernie Gristwood said she made the trek to see "what all the excitement was about."

"I think everyone's worried about spending money but I think with what is here, with the outlets, a smart shopper can make some good purchases," said Gristwood.

Rita Henderson went to the mall looking for back-to-school deals for her children.

"Everything's expensive, especially school, so you just have to make sure they have what they need," she said.