Tonight an amazing survival story from a woman who says her first decision was, don't die. Her car was struck just days ago, hurled from a bridge into the water and as it began to sink she says she... See More
Tonight an amazing survival story from a woman who says her first decision was, don't die. Her car was struck just days ago, hurled from a bridge into the water and as it began to sink she says she willed panic into calm and her next decision saved her life. Abc's lisa stark shows us how she did it. Reporter: It was around 8:00 at night, 22-year-old morgan lake at the wheel of her chrysler sedan on the chesapeake bay bridge. I saw my car explode with glass flying everywhere and airbags coming at me full force. Reporter: An 18-wheeler moving at full speed had smashed into her from behind. Lake says he car rode up on the three-foot high barrier on the side of the bridge and went flying, teetering briefly at the top then plunging 27 feet to the water below. My eyes were closed, my mouth filled up with water. I got one good scream in and i started to drown. Reporter: She told herself, "i don't want to die." I visualized my car, took my right hand, pushed the seat belt, turned to the left side, the window was alreadyken, went though it, pushed off to get momentum to get to the surface. Reporter: Lake did just what she should have, as we saw during a demonstration with experienced divers, police say most people do the wrong thing, reach for their cell phone to call for help. Instead, just get out fast. The four men inside react instantly. The critical steps -- seat belt off, windows down, get out. Here it is again, as you can see, there is time to escape if you act quickly. The first 30 to 60 seconds is when you have to get out of that vehicle. Reporter: But what if your window won't open? Keeping a simple window-break tool within reach in the car can save your life. That's it. Done. Reporter: Tonight, lake has some advice of her own. I want to inspire anyone out there that I can -- don't give up. Reporter: Lisa stark, abc news, washington.
This transcript has been automatically generated and may not be 100% accurate.