An "unusual note" found on board a Minneapolis-to-Atlanta Delta Air Lines flight Friday morning prompted the crew to declare an emergency "out of an abundance of caution," according to the airline.

The crew of Flight 1747 reported that passengers found the note about 40 minutes from Atlanta, said spokeswoman Susan Elliott.

"The flight landed without incident and passengers were deplaned normally," she said in an e-mailed statement. "We are cooperating with federal authorities as they investigate the origin of the note."

Delta did not say what the note said but the Atlanta Journal-Constitution cited an Atlanta police dispatch log as saying that a customer feedback card was found in a seat pocket on Flight 1747 stating, "This plane will go down."

The passengers who discovered the note were interviewed before they continued to their final destination, Transportation Security Administration spokesman Jon Allen told the Journal. "The flight was swept by a canine team with negative findings."

SUZANNE ZIEGLER