Carrie Fisher's Family Wants to Thank Heroic United Passengers

Carrie Fisher's family is on the hunt for the off-duty emergency workers who came to her aid on a United jet when her heart stopped.

Family sources tell us ... they believe 2 people on Carrie's flight deserve a big thank you for their valiant effort. Flight attendants jumped on the P.A. asking for medical professionals to come forward ... and they did.

We're told these 2 volunteers -- one of whom is a nurse -- "worked like crazy" to keep Carrie alive, despite the fact they couldn't get a pulse for more than 10 minutes. The family believes if it wasn't for them, they wouldn't have had a few extra days to say goodbye.

The family will contact United to see if they can locate the passengers.