A plane flying from Ireland landed in Philadelphia unexpectedly after receiving an "unsubstantiated" threat, according to the Philadelphia police and reported by NBC News. After investigating the situation, the police found the threat was unfounded.

The plane was taken to a remote area of the airport as a precautionary measure to allow Philadelphia police and Homeland Security to search the passengers and luggage.

"Once we landed, all of a sudden we saw all these cop cars," Molly Cross, one of the passengers, told NBC. "An FBI agent got on the plane and told us that someone made a bomb threat or something like that."

The threat was called in to the Philadelphia Airport by an unidentified male, according to sources near the investigation who wanted to remain anonymous because they weren't authorized to speak publicly about the case.

The landing wasn't an emergency situation. The flight, US Air Flight #777 took off from Shannon airport in Ireland and was scheduled to arrive at Philadelphia International Airport at 2:05 p.m. The flight landed at 1:58 p.m., according to the US Airways web site.

"We were aware of a possible security issue with the flight and out of an abundance of caution, taxied the aircraft to a remote location, where it was met by law enforcement and emergency personnel," Davien Anderson, a spokesperson for U.S. Airways, said.

All the passengers, as well as eight crew members, were escorted off the plane and loaded onto buses. They were then taken to a secure area, where they were screened and interviewed. The luggage was removed and screened and bomb-sniffing dogs went through the plane, which is the standard procedure.

"They got everyone off," Cross said. "They got buses and everything and the dog sniffed our bags.

"We got interviewed," Cross continued. "They just asked basic questions, like how long I was there."

Inbound flights were temporarily delayed for the duration of the investigation, according to Victoria Lupica, a spokeswoman for the Philadelphia airport.

In a situation such as this one, the FBI and Homeland Security are alerted, and the Joint Terrorism Task Force is called in to help with the investigation.

News coverage of the threat.