PORTLAND, Ore. - A family is grieving after a 22-year-old man collapsed and died during his brother's birthday party.

The sudden death happened at a home on Southeast Lillian Way near Powell Butte.

Witnesses told police that Tanner McKee and his younger brother, who just turned 18 years old, were wrestling around or boxing when McKee suddenly collapsed and stopped breathing after getting hit in the back.

"I didn't know what to do," said Kevin Bonphisoi, a friend. "I held his head up, he started breathing, he stopped breathing, he started again. We called 911."

An autopsy was conducted on Sunday.  The findings were inconclusive but showed no evidence of trauma.  Further testing and a toxicology examination will be done to try to determine the cause of death.

According to police, because there was no evidence of trauma, investigators concluded that McKee did not die from a blow or strike from his brother.