UPDATE: (AP) BREAKING: Mexico official says SurveyMonkey CEO Dave Goldberg died of severe head trauma in an exercise accident.

The official said he left his room at about 4 p.m. to exercise, and family members went to look for him after he didn’t return. He was found at about 6:30 p.m. in one of the resort’s gymnasiums lying by a treadmill in a pool of blood, with a blow to the lower back of his head. He apparently had slipped on the treadmill and hit the machine, said the official, who spoke on condition of anonymity because the person was not authorized to speak to the press. Full report here.

Adelle Nazarian’s original report begins in full here:

Three days after news of Survey Monkey CEO Dave Goldberg’s mysterious death, it has been reported that Friday he died while exercising at the gym of a private resort in Mexico.

Goldberg was vacationing with his wife, Facebook COO Sheryl Sandberg, their two children and friends.

“Efforts to revive him at the gym and at a hospital were unsuccessful,” an anonymous family friend told the New York Times. The family has opted to keep the information surrounding his death private.

An official cause of death has not yet been confirmed by a coroner.

Goldberg, 47, was pronounced dead on Friday evening yet his brother Robert Goldberg made the information public on Saturday through a Facebook post, which said he had “passed away suddenly” and did not provide any further details.

Blogger, entrepreneur and “geek feminist” Penelope Trunk speculated openly that Goldberg’s death was a suicide. Further curiosity has been roused by the fact that Goldberg’s body was left in Mexico, while his wife and children returned to California.

The anonymous source told Forbes that further information surrounding Goldberg’s death would be released when available. The source did not reveal at which Mexican resort the family was staying. An autopsy is reportedly being conducted on his body.

Sandberg has yet to make a public announcement about her husband’s sudden death and the family has requested privacy as they cope with his loss. A private reception honoring his life will be held in Silicon Valley on Tuesday.

Survey Monkey released a statement following his death, that friends and relatives have poured comments, memories, and heartfelt tributes to Goldberg on his own Facebook page.

Follow Adelle Nazarian on Twitter @AdelleNaz