Alyssa Milano in car crash after uncle has heart attack at wheel

Alyssa Milano's knowledge of CPR likely may have helped keep her uncle alive after he suffered a heart attack on Tuesday while behind the wheel on a Los Angeles freeway and smashed into another car.

"Yesterday my family suffered a terrifying and traumatic event," Milano, 48, wrote Wednesday on Instagram and Twitter. "I was a passenger in a car my Uncle Mitch was driving when he suffered a serious heart attack resulting in a car crash."

The "Charmed" and "Who's the Boss?" star went on to express her gratitude for the people who stopped to help them.

"I'll never be able to thank them enough for the care and attention they, along with the first responders, doctors, nurses and staff at UCLA Medical Center paid to him and to me," she added.

According to a California Highway Patrol release obtained by People magazine, Milano's uncle, Mitchell J. Carp, drifted into another lane after becoming unconscious following his heart attack. The vehicle collided with a black SUV and was eventually brought to a stop between lanes "with the assistance of a good Samaritan," the release stated.

TMZ, which was the first outlet to report the accident, said that Milano, who was unharmed, administered CPR on Carp until first responders arrived. Carp was transported to UCLA Westwood Hospital. His status is still uncertain.

Milano was picked up by her husband and brought home.

In her social media post, Milano urged everyone to become CPR certified: "You don't know when you'll be called upon to save a life. The American Red Cross and many hospitals and other organizations offer regular classes. It's such a small effort and can have a huge impact."