BOSTON (AP) - A flight from Las Vegas to Paris made an unscheduled landing in Boston on Thursday (Jan 9) after passengers described hearing a loud noise and for what the airline called a mechanical issue.

The crew of the Delta Air Lines flight reported a vibration and declared an emergency before landing safely at about 9.30pm, FAA spokesman Rick Breitenfeldt said in an email.

The aircraft had a "mechanical issue" and a maintenance crew was evaluating the aircraft, Delta spokeswoman Emma Protis said in an email.

No details were disclosed.

"All of a sudden a loud noise in the plane. Confusion. People panicking," passenger Jona Kallgren wrote on Twitter.

The airline said it was providing another aircraft to bring the passengers to Paris.