A behind the scenes look at security in biggest mall in US

BLOOMINGTON, Minnesota  — The Mall of America has provided a rare glimpse into security at the busiest U.S. shopping center after an online video purportedly produced by a terrorist group urged extremists to attack shopping malls in Western countries.

The Bloomington megamall has some 40 million visitors each year, and the behind-the-scenes steps taken to keep visitors safe are generally unknown to shoppers.

Officers patrol the mall with family-friendly dogs trained to sniff out bombs. A security team stationed at an underground nerve center keeps watch on hundreds of security cameras throughout the shopping center. Delivery trucks are swabbed for explosives before merchandise in unloaded.

This is a safe place," Bloomington Police Chief Jeff Potts said. "We encourage people to come on out and shop."

Officials said most safety measures have long been in place, but that it's stepped up security following the threat.

"We've dealt with this sort of thing in the past," Potts said. "For a lot of really good reasons, we've been working with partners in local, state and federal law enforcement for years. We have built our contingency plans."

Potts said his officers have increased their presence since the recent threat, but he would not say how many police officers are on duty at the mall. The mall separately employs 100 full- and 50 part-time security staff.

The video purportedly made by Somalia's al-Qaida-linked rebel group al-Shabab urges Muslims to attack shopping malls in the U.S., Canada, Britain and other Western countries. The masked narrator specifically names the Mall of America, as well as shopping centers in Canada and England.

U.S. authorities say there is "no credible" evidence suggesting a U.S. mall attack is in the works.

The authenticity of the video could not be immediately verified by The Associated Press.