American Airlines says a mechanical issue has forced a plane to return to the gate at Boston’s Logan Airport, and four people have been taken to hospitals to be evaluated.

WCVB-TV reports the airline says passengers reported an odor in the cabin Monday before the plane was scheduled to leave Boston. It was headed to Charlotte.

Officials say the plane returned to the gate and three crew members and a passenger were taken to hospitals.

The Massachusetts Port Authority confirmed that four people were transported. The airline says the plane was taken out of service because of a mechanical issue and the passengers would be transported on a different plane.