Updated

A US Airways flight bound from New York to Phoenix was diverted to St. Louis Tuesday after three passengers acted suspiciously, the Transportation Safety Administration said.

A statement from TSA said US Airways flight 457, which took off from John F. Kennedy Airport in New York, landed at Lambert Airport shortly before 8 a.m. TSA spokeswoman Sarah Horowitz would not elaborate on what exactly prompted the crew to consider the three passengers suspicious.

Lambert spokesman Jeff Lea said the plane landed without incident. TSA has not said if anyone was taken into custody.

Valerie Wunder, a spokeswoman for Phoenix-based US Airways, said the plane was checked and cleared, as were the 128 passengers. The plane was expected to resume its flight to Phoenix later Tuesday morning.

Wunder would not disclose what prompted the security concern, deferring to the TSA.

The incident comes amid heightened awareness around the 10th anniversary of the Sept. 11, 2001, terrorist attacks.

On Sunday, a GoJet Airlines flight from St. Louis to Washington returned to the gate at Lambert before taking off, after crew became concerned when they found paper towels stuffed in a toilet. Passengers were re-screened, the plane took off again and landed at Dulles Airport in Washington about an hour later than scheduled.

Also Sunday, fighter jets were scrambled to escort two commercial flights into New York City and Detroit after crews reported suspicious activity. Bathroom use was also cited in those incidents: On an American Airlines flight from Los Angeles to John F. Kennedy Airport, three passengers made repeated trips to the bathroom; and on a Denver-to-Detroit Frontier Airlines flight, the crew reported two people were spending "an extraordinarily long time" in the bathroom.

The passengers deemed suspicious were cleared in both of those cases.