A US Airways flight to Dallas was called back to Philadelphia on Thursday morning and surrounded by police after law enforcement officials received an anonymous tip that liquid explosives were on board, an FBI spokesman said.

Special Agent Frank Burton said it wasn't immediately clear if the tip involved a specific person or a specific flight. Transportation Security Administration spokesman Dave Castelveter said US Airways Flight 1267 returned "due to a report of a suspicious item on board."

After landing, the airplane taxied to a remote section of Philadelphia International Airport, where a slew of law enforcement vehicles surrounded it. Law enforcement officials could be seen removing a person from the flight and putting him in the back of a police car.

The airplane bound for Dallas-Fort Worth International Airport had 69 passengers and five crew members on board, airport spokeswoman Victoria Lupica said. It left Philadelphia around 8 a.m. and returned in less than an hour, she said. The jet was over central Pennsylvania, near Harrisburg, when it turned around, according to the flight-tracking website FlightAware.

No other flights were affected, Lupica said.

US Airways spokesman Todd Lehmacher said the passengers would be put on a later flight.

Philadelphia police referred all calls to the FBI.