College Student's Amazing Lake Rescue of 92-Year-Old Driver

— -- A Florida college student who hopes to one day be an ER doctor saved his first life when he dove into a lake to rescue an elderly man who was trapped unconscious in his car after the vehicle had plunged into the water.

Alton Brieske, 21, was having lunch on Wednesday in Port St. Lucie when he saw the car smash through the bushes and plummet into the water, he told ABC affiliate WPBF.

"I ran over here, immediately took my shirt off and threw everything right there, and just dove in the water," said Brieske, a pre-med student at Florida Atlantic University who hopes to eventually be an ER doctor.

He swam to the car, but the driver, Salvatore Mancuso, 92, was unconscious. Brieske noticed a crack in one of the windows, and water was flowing into the car.

"When that happened, that's when I was like, 'All right, we need to get him out of here, because it's going to sink any time now,'" he told the station. "I started screaming, 'I need a hammer! I need a hammer!' Then some guy comes running through the bushes, and he's like, 'I got one.'"

Video shows Brieske smashing the window with the hammer. Other bystanders had jumped in the water to help.

"I broke that window, popped the lock, opened the door," he told WPBF. "That's when the water started rushing in, so I just acted fast, popped his seatbelt off, put my arm under his shoulder and got him out of the car."

Brieske swam Mancuso to shore, but Mancuso wasn't breathing, so Brieske performed CPR, police said.

Police and fire rescue arrived and took Mancuso to a hospital. He remains in the ICU, police said.

Investigators are trying to determine if Mancuso experienced a medical emergency before the crash.

Brieske shuns his new label as a hero.

"I'm a not a hero," he told WPBF. "That was my calling for today, to save this guy. I was just in the right place at the right time."