10/29/2010 05:28 pm ET Updated May 25, 2011

Chicago Synagogue Threat: FBI Tells Religious Institutions To Be Cautious

Chicago-area synagogues are on high alert Friday after it was discovered that two packages containing explosive materials were addressed to places of Jewish worship here.

President Barack Obama said Friday that officials had uncovered a "credible terrorist threat" against the United States following the overseas discovery of U.S.-bound packages containing explosives aboard cargo jets.

The disclosures triggered a worldwide alert amid fears that al-Qaida was attempting to carry out fresh terror attacks.

According to the Chicago Tribune, one package intercepted in England on a flight from Yemen contained a "manipulated" toner cartridge "with wires and circuitry attached." The other package was discovered in Dubai.

While there is a synagogue across the street from President Obama's Chicago home, neither package was addressed to that location, officials told the Tribune. Obama will be near his Hyde Park home Saturday for a rally.

The events "underscore the necessity of remaining vigilant against terrorism," the president said. The packages both originated in Yemen, but Obama did not explicitly assign blame to al-Qaida, which is active in the Arab nation and long has made clear its goal of attacking the United States.

FBI Special Agent Ross Rice told CNN that Chicago's religious institutions should be extra careful when opening any packages.

"Since two of the suspicious packages that were intercepted were addressed to religious institutions in Chicago, all churches, synagogues and mosques in the Chicago area should be vigilant for any unsolicited or unexpected packages, especially those originating from overseas locations," Rice told CNN.

According to NBC Chicago, one of the targeted locations was the Temple Sholom synagogue at 3480 N. Lake Shore Drive. The second location was reportedly a Jewish Community Center.

"We hear about terrorism all the time, but we often feel Chicago is not on the radar for that, but this is a reminder it is," Rabbi Asher Lopatin, who leads a Lakeview synagogue, told NBC. "Our office gets toner cartridges all the time. We obviously have to be more careful about that. We are not accepting packages until our security screens them first."

White House counterterrorism adviser John Brennan later told reporters that the explosives "were in a form that was designed to try to carry out some type of attack," but he provided no further details.

"The forensic analysis is under way," he said, adding, "Clearly from the initial observation, the initial analysis that was done, the materials that were found in the device that was uncovered was intended to do harm."

Jewish Federation of Metropolitan Chicago spokeswoman Linda Haase told CNN the organization was "taking appropriate precautions" and telling other local synagogues to do the same.