An Air Canada flight bound for Halifax on Wednesday from Newark, N.J., was diverted to Boston after its captain suffered a medical emergency.

A passenger told ABC News that the plane started “swerving violently” and the captain was then removed from the cockpit, appearing to be suffering from a seizure and incapacitated.

The first officer took control of the aircraft and safely landed the plane in Boston, Air Canada said in an email to CBC News.

The airline said the captain of Flight 7664 was removed from the flight deck “per safety protocols” and the plane, a De Havilland Q400, landed at Boston Logan International Airport.

The Massachusetts State Police said the flight was diverted at 1:40 p.m. local time after a crew member reported a medical emergency.

The airline said the captain was taken for medical treatment in Boston.

Rodney McDonald, who was a passenger on the flight, told ABC News he knew something was wrong “the moment the plane swerved.”

McDonald told ABC News a flight attendant rushed into the cockpit and pulled one of the pilots into the aisle. McDonald said the pilot appeared to be experiencing a seizure and a registered nurse on board helped direct passengers to assist the pilot.

Air Canada said the flight, which was operated by its regional partner PAL Airlines, carried 61 passengers and that work is underway to help them make new travel arrangements “to complete their journeys as soon as possible.”

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