Federal officials warned Mall of America visitors to "be particularly careful," but all appeared to be business as usual at the Bloomington megamall Sunday.

The cautionary message came from Jeh Johnson, U.S. secretary of Homeland Security, after the Somali terrorist group Al-Shabab released a video calling for attacks on Western malls. The video specifically mentioned the Mall of America, which gets an estimated 40 million visitors annually.

"If anyone is planning to go to the Mall of America today, they've got to be particularly careful," Johnson said in a televised interview with CNN Sunday morning. "There will be enhanced security there, but public vigilance, public awareness and public caution in situations like this is particularly important, and it's the environment we're in, frankly."

Still, by midafternoon, drivers were jostling for spots in the parking ramp and the mall's four levels were crowded with shoppers. Several store clerks said it seemed to be a typical Sunday.

Another Homeland Security official later clarified that Johnson was not urging people to stay away from the mall.

"Secretary Johnson didn't say that they should not go to the mall," assistant secretary Tanya Bradsher told CNN. "He told shoppers to be extravigilant and that security was increased."

Just one day before the video's release, Al-Shabab militants attacked a popular hotel in Mogadishu, Somalia with a car bomb and suicide bomber, killing at least 25 people.

Late Sunday afternoon, Bloomington police released a statement on behalf of the mall and federal, state and local law-enforcement agencies that said, "At this time, there is no credible threat associated with Mall of America" in connection with "the recently released propaganda video." The mall remains "a very safe place," and additional security personnel have been enlisted, the statement said.

Johnson, on CNN, said he was "very concerned" about the threat because "these groups are relying more and more on independent actors to become inspired, drawn to the cause … through their effective use of the Internet."

Johnson's concern no doubt is related to the fact that the Mall of America is located in the metro area with the largest Somali population in the United States. Just between 2007 and 2009, at least 22 young Somali-Americans left the Twin Cities after being recruited to join Al-Shabab. Officials say another 15 have left Minnesota in recent months to join Islamic State in Iraq and the Levant (ISIL).

In 2005, the mall started a special security unit whose officers look for unexplained nervousness, people photographing such things as air-conditioning ducts or signs that a shopper might have something to hide, according to records.

An ordinary Sunday at MOA

From outside the mall Sunday, there was no overt sign of intensified security as visitors arrived. Mall spokeswoman Sarah Schmidt said that it unfolded just like any other weekend day at the destination popular with tourists and locals alike.

One visitor to the mall Sunday morning said it was 45 minutes before she saw her first uniformed security officer, and a handful of other shoppers seemed unfazed by the attention given the mall by terrorists. Later, small groups of Bloomington police officers and private guards were seen making the rounds of the mall.

"I'm more afraid of the cold today than any terrorists," Mary Lamminen, of St. Paul, said on a day when the temperature remained below zero until midafternoon.

Several store managers said they noticed no drop-off in crowds as of the afternoon, and the parking lots were crowded.

Nancy Cashion was visiting Sunday with her daughter, Melanie Isabell. Both said they were aware of the terror video. "There's probably a lot of threats we don't even hear about," Isabell said.

'Pure evil'

U.S. Sen. Amy Klobuchar of Minnesota said she spoke Sunday morning with Andy Luger, the U.S. attorney in Minnesota about the video and, "we've been in contact with Homeland Security, and I know that everyone is focused on how to protect the mall."

In an interview with WCCO-TV, Channel 4, the Democrat added, that "we've seen [Al-Shabab] try to recruit people; they've done these sophisticated videos before … showing plane tickets from Minneapolis to Somalia. … These groups are pure evil."

Last week, Luger led a Minnesota delegation, including law-enforcement officials and Somali community leaders, to a White House summit on extremism and radicalization. In remarks, Vice President Joe Biden pointed to Minneapolis, Boston and Los Angeles as pursuing programs to counter extremism locally.

In a second Sunday morning news show interview, on ABC-TV, Jeh Johnson said the threat against the Mall of America represents a "new phase [in] terms of the global terrorism threat … that is more complex, more decentralized, more diffused. … It encourages strikes with very little notice to our intelligence community, our law enforcement community here at home."

Fighters urged to 'hurry up'

The Mall of America increased security Saturday after Al-Shabab's video was released. A statement issued by the mall Saturday said it was aware of a video that mentions and shows images of the Bloomington megamall, and that it has "implemented extra security precautions."

"Some may be noticeable to guests and others won't be," the statement read. "We will continue to follow the situation along with federal, state and local law enforcement and will remain vigilant as we always do in similar situations."

The Al-Shabab video, circulating on Twitter, is more than an hour long and focused on the September 2013 attack on the Westgate Shopping Mall in Nairobi, Kenya. At least 67 people died in that siege. The Mall of America also increased security in the aftermath of that attack.

At the end of the video, a masked man says: "If just a handful of mujahedeen fighters could bring Kenya to a complete standstill for nearly a week, then imagine what the dedicated mujahedeen in the West could do to American — or Jewish-owned shopping centers across the world? What if such an attack were to occur in the Mall of America in Minnesota? Or the West Edmonton Mall in Canada? Or in London's Oxford Street?"

The man, his face wrapped in a black-and-white kaffiyeh-type scarf and wearing a camouflage jacket, spoke with a British accent. He urged fighters to "hurry up."

The Mall of America and the West Edmonton Mall were both developed by the Ghermezian family, whose members immigrated to Canada from Iran in the 1960s and are of Jewish background.

In Alberta, Sgt. Brent Meyer of the Royal Canadian Mounted Police said the force is aware of the Al-Shabab video, but "there is no evidence at this time of any specific or imminent threat to Canadians."

Meyer said authorities "take this threat to our national security very seriously [and will] continue to monitor events" in concert with other law enforcement agencies.

Star Tribune staff writer Pat Pheifer and the Associated Press contributed to this report. Paul Walsh • 612-673-4482