UPDATED: May 2, 1011 3:55 p.m.

CHICAGO (CBS) — Following the death of terror mastermind Osama Bin Laden, the question on many minds: Will al-Qaeda retaliate and if so when and where?

In Chicago, security officials aren’t taking any chances–even though there is no specific terrorist threat. The NBA has ordered metal detectors added at all arenas to screen fans — and tonight’s playoff game at the United Center is no exception.

The game between the Bulls and the Atlanta Hawks was the first large gathering of people in Chicago since the news that Bin Laden had been killed in an U.S. military operation.

Besides the United Center, additional security measures are clearly being taken across the city.

Roderick Drew, the spokesman for the city Office Of Emergency Management and Communications, emphasized that there is no known terrorist threat against Chicago, but urged “if you see something, say something” and report suspicious activity to 911.

There will be more uniformed police visible on the streets and security officials will be closely watching Chicago’s vast array of surveillance cameras.

“We remain vigilant and alert. [The] heightened alert has been heightened a little more when it come down to that,” said Police Supt. Terry Hillard.

The FBI and Department of Homeland Security are warning law enforcement across the country that bin Laden’s death will likely inspire homegrown extremists in the U.S. to try to carry out attacks in the near-term.

The agencies issued a joint intelligence bulletin Monday that said the core al-Qaida group is less likely to carry out attacks against the U.S. in the immediate future, but its spinoff groups around the world could use bin Laden’s death as an excuse to speed up plans for attacks.

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The Chicago Tribune reports that Chicago police are focusing on mosques, synagogues and churches, particularly in the Rogers Park and West Rogers Park neighborhoods as a precaution. However, there was no specific threat reported against any group.

The city has taken the following steps in the wake of the U.S. raid that killed bin Laden:

  • All Chicago Police Department personnel will be in uniform.
  • Key personnel with the Chicago Fire Department and Chicago Department of Aviation have also been notified to remain vigilant.
  •  Security officials have been actively monitoring cameras citywide, including cameras in the Operation Virtual Shield surveillance camera network, with special emphasis on critical infrastructure.
  • City of Chicago officials have been in contact with the Department of Homeland Security (DHS), as well as federal and state law enforcement officials, to share and distribute information to law enforcement officials and emergency responders.

Metra spokeswoman Judy Pardonnet said passengers will notice security measures but added the rail agency is also taking “some action that is behind the scenes that the commuters would never notice.”

The Willis Tower has been on the Al-Qaeda target list, and security measures were taken to keep it and the people inside safe. There were no signs of increased security outside, but many visitors had security on their minds.

“There’s always a little bit of concern, but I’m confident as to the security levels and security features that all these buildings have so I feel pretty safe,” said tourist John Capiro.

Tourist Terri Ogden-Oyler decided to skip a tour of the tower out of an abundance of caution: “We’ve chosen to go somewhere else.”

For those traveling via airlines, the State Department is urging Americans to limit travel outside of their homes and hotels, and to avoid mass-gatherings.

At O’Hare International Airport, increased security checks made for longer lines, but travelers didn’t mind.

“I’m OK,” said Colleen Jones, who was traveling to Barbados. “A little tense but OK … anything to keep me safe and to get to our destination.”

The CTA reminded employees to be on the lookout for any suspicious activity.

And similar security concerns prompted Metra to increase police presence at its stations and platforms.

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