Former Wings guitarist Henry McCullough is in a critical condition in hospital after suffering a heart attack.
The 69-year-old from Portstewart, Northern Ireland, was taken ill on Monday night.
McCullough, who played with Joe Cocker at the famous Woodstock festival in 1969, is being treated at the Causeway Hospital in Coleraine.
A spokeswoman for the hospital said he was in a "critical condition".
The rock guitarist embarked on a successful solo career after his time playing with Paul McCartney in Wings.
He is perhaps best known for his playing on Wings' number one hit "My Love".
His sister Rae Morrison said the family were very distressed.
"He is very special person," she said. "It really is a very worrying time for us."