We have all heard stories about a person lifting a car in a moment of panic to save someone trapped beneath. This phenomenon is called hysterical strength, and seems to be triggered by life-or-death situations, but as far as I know, it has never been actually documented. Still, anecdotes abound, and they almost all are examples of lifting a vehicle off of someone.
When a 1964 Impala slipped off its jacks and pinned Georgia man Tony Cavallo underneath in 1982, his mother Angela was able to lift up the heavy car while neighbors replaced the jacks and pull Tony to safety. When a Camaro hit Kyle Hurst in Tucson, Arizona in 2006, the boy was trapped until onlooker Tom Boyle lifted the car off of him while the driver grabbed Kyle.
Other stories are echoes of the same: A Kansas man lifting a Mercury off a 6-year old in 2009, a college football player lifting a cadillac off a tow-truck driver in 2011, a man in Newfoundland lifting a truck off a boy in 2015. In 2013, two teenage girls lifted a tractor off of their dad in Oregon.
Two of the anecdotes occured in my home state of Virginia, within the last 6 years. A 22 year-old woman in Glen Allen lifted a BMW off of her father after his jack slipped in 2012. She then went on to perform CPR and save his life. Several years later, in 2015, a Vienna woman repeated the theme, rescuing her dad from underneath a burning pickup truck, then driving the truck away from their house.
Lydia Angiyou
In the one recent instance I could find that didn't involve a vehicle, a woman in northern Quebec fought off a 700 lb polar bear in order to save her son and his friends. The group was walking outside when they saw the bear coming for them, and Lydia Angiyou told the kids to run. She then attacked the bear, punching and kicking it before she was knocked down. With the bear on top of her, she continued to fight and wrestle it, until a neighbor was able to get his rifle and kill the bear.