Rescue teams used chain saws to cut the massive tree apart and get to the injured. A group of people were on a lawn-bowling field when part of the tree came smashing down.
"Out of the blue the tree shook a little bit, and we looked up and it was started coming down. And then there was this horrific crack. I mean, it was just horrific. And so I heard people were saying 'run for your life,'" said Lawn Bowling Club President Larry O'Dea.
Two members of the lawn bowling club got caught under the branches but one of them was able to get out quickly.
"The elderly lady had a whole bunch of branches over her, and her ankle was snapped in half towards the top. So, and she had a big, big cut through the side of her head," said witness Humberto Mirales.
A San Jose Fire Department spokesperson said her injuries looked bad, but they were minor. She was taken to a local hospital as a precaution.
The massive oak actually split in two with one half falling on the lawn bowling field and the other half crashing onto several cars parked on the street.
At least one person in a vehicle was taken to the hospital with minor injuries.
The lawn bowling club was hosting an event for the defensive coaching staff of the San Francisco 49ers. All five of the coaches escaped injury.
"Just unbelievably lucky that only one person was seriously injured," said O'Dea.