Former MLB pitcher Roy Halladay, a two-time Cy Young Award winner and eight-time All Star, has died in a plane crash at the age of 40.

Pasco County Sheriff's Office confirmed Halladay died after the single-engine plane he was flying crashed into the Gulf of Mexico off the coast of Florida on Tuesday. Nobody else was on board.

A statement on @PascoSheriff read: "RIP Roy Doc Halladay, a true baseball great and a man with a generous heart. Our thoughts and prayers are with Roy and his family during this difficult time."

Halladay won the Cy Young Award - given annually to the two best pitchers in the MLB's American League and National League - in 2003 while playing for the Toronto Blue Jays and again in 2010 while with Philadelphia Phillies.

The right-hander is one of only six pitchers in MLB history to win the award in both leagues, while in 2010 he became only the second player to throw a no-hitter in the post-season.

The Blue Jays paid tribute to Halladay, who spent 11 years in Toronto.

"The Toronto Blue Jays organisation is overcome by grief with the tragic loss of one of the franchise's greatest and most respected players, but even better human being," Toronto said in a statement.

"It is impossible to express what he has meant to this franchise, the city and the fans.

"Our thoughts and prayers are with his family and friends."

The Phillies, who Halladay represented from 2010-13, said in a statement: "We are numb over the very tragic news about Roy Halladay's untimely death.

"There are no words to describe the sadness that the entire Phillies family is feeling over the loss of one of the most respected human beings to ever play the game. It is with the heaviest of hearts that we pass along our condolences to Brandy, Ryan and Braden."