Passengers traveling on two separate American Airlines planes were quarantined in Philadelphia on Thursday afternoon after becoming sick with flu-like symptoms, airport officials said.

A dozen travelers on Flight 755 and Flight 717 complained of feeling ill after departing from their planes at Philadelphia International Airport.

The passengers are believed to have been returning from Saudi Arabia after completing Hajj - the pilgrimage to Mecca which all Muslims are expected to make at least once in their lifetimes.

As a precaution, all passengers and crews from both flights were held for medical review, according to an airport spokeswoman. A total of 250 people were evaluated, and the Centers for Disease Control and Prevention was notified.

CDC officials said people who are healthy are being released. They also said neither plane was quarantined because passengers reported feeling sick after disembarking.

A dozen people on two separate American Airlines planes were quarantined in Philadelphia after falling ill

Flight 755 originated in Paris and landed in Philadelphia in the afternoon. Flight 717 originated in Munich, Germany and landed in Philadelphia around the same time. NBC Philadelphia reports that numerous travelers were returning from pilgrimages in Mecca, Saudi Arabia before boarding in Paris and Munich.

Customs and Border Protection officials said most of the passengers on the Philadelphia-bound flights have been released. Several are still being evaluated by the CDC of local doctors.

Health officials said after the scare in New York on Wednesday, they are taking 'an abundance of caution' in Philadelphia.

There has been reports of a flu outbreak in Mecca, where more than one million religious observers have traveled to for Hajj, an annual Islamic pilgrimage . It's unclear how many may have become ill during their travels.

On Wednesday, an Emirates fight from Dubai to John F Kennedy Airport in Queens was quarantined after 19 people became ill with what was described as flu-like symptoms.

One passenger on the Emirates flight in New York on Wednesday was seen being transported on a stretcher by paramedics to an ambulance

A passenger shared photos of passengers (left and right) getting their temperatures taken as they got off the plane in New York on Wednesday

Many of the healthy passengers described hearing fellow travelers violently coughing during the flight. Ten people - seven crew members and three passengers - were hospitalized, while nine others refused medical treatment.

In a series of tweets on Wednesday, City Hall spokesman Eric Phillips said early reports indicated that passengers had been become sick with the flu.

'All of the passengers are off and have been evaluated. 19 sick. 10 to hospital and 9 refused medical attention,' he posted. 'Health officials are processing tests now to determine the cause. Symptoms still pointing to the flu.'

The double-decker Emirates flight, which rapper Vanilla Ice was on, originated in Dubai. According to reports, several of the passengers had traveled to Mecca for the religious pilgrimage.