Many Americans celebrated the death of Osama bin Laden Monday, but for some the sense of relief is also accompanied by a fear of retaliation.
As he announced bin Laden's death, President Barack Obama stressed, "There's no doubt that al Qaeda will continue to pursue attacks against us."
Sen. Joe Lieberman, I-Conn., who leads the Homeland Security Committee, said all relevant federal agencies are on alert and "using every tool they have to detect and react (to potential threats)."
"My only great concern in the days ahead is that a so-called lone wolf, a single individual who has been radicalized, will now mobilize himself or herself to take action here at home against the American people," Lieberman said Monday.
Police forces in major cities like New York City, Washington, D.C., and Los Angeles have increased their presence in high target areas over concern that terrorists will seek revenge.
Security at major transportation hubs like subways and airports can expect a show of force in the coming days.
Sen. Susan Collins, the top Republican on the Committee, also urged Americans to be on alert for suspicious activity here at home.
"We must continue to be vigilant. I agree that one of the concerns that I most have is that a homegrown terrorist will choose this moment to strike in an attempt to retaliate for Osama bin Laden's death," Collins said.
CBN News Reporters John Waage, George Thomas, and Chuck Holton talked more about the growing fears, and possible attacks at home and abroad.
Stay with CBNNews.com for their analysis.
The Port Authority of New York and New Jersey added more police, saying the agency is acting not based on a current threat, but out of an abundance of caution.
Police in Philadelphia, Penn., are also on heightened alert, checking on mosques and synagogues every hour.
In Washington, D.C., capitol police also patrolled the U.S. Capitol in force, Monday, as lawmakers returned from their Easter recess.