The four officers who rescued an 18-month-old toddler from the wreck of a submerged car on Sunday said they launched into their heroics when they heard desperate pleas for help coming from a woman inside.

But when the four men used all their strength to right the red Dodge sedan, they found little Lily Groesbeck to be the only passenger left alive in the vehicle.

Her mother, 25-year-old Lynn Jennifer Groesbeck, had passed away the night before when she lost control of the car and could not possibly have called for the men to help save her child.

'For two nights I've laid awake trying to figure out exactly what it could be. All I know is it was there, we all heard it,' Spanish Fork Police Officer Tyler Beddoes said. 'It was extra motivation.'

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Lone survivor: 25-year-old Lynn Jennifer Groesbeck (left) and her 18-month-old daughter, Lily (right), were found inside a crashed car in Utah's Spanish Fork river on Saturday. Groesbeck pictured above in a photo posted to Facebook

Spanish Fork Police Officers Tyler Beddoes, left, and Jared Warner, right, and Spanish Fork City Firefighters Lee Mecham, second from left, and Paul Tomadakis, second from right, answered questions Monday night regarding be the first responders on scene

Submerged: The temperature in the river was near freezing throughout the night after the car hit the river. Water flowed into the car through broken windows and rushed just below Lily's head

Tragic: Groesbeck died in the crash, but her baby, Lily, survived, is in stable condition and is improving. She is opening her eyes and doing well, police said

Beddoes said that he and the other three on scene responded to the voice calling for help when they approached the car.

All four officers said they were there to help. But when they flipped the car, the mother was already deceased and Lily was unconscious, he said.

A firefighter jumped into the river and cut the straps, freeing the blond baby girl who was wearing only a flannel onesie and no hat or gloves.

Officers formed a line in the river and handed the cold girl to one another until she was on the shoreline and in emergency workers' arms. They rushed her to an ambulance and performed CPR, Beddoes said Monday, two days after the crash.

Lily is in stable condition and improving, according to hospital officials. Beddoes, who spoke with the family, said the baby is opening her eyes and doing well.

'Her improvement is astounding. Right now she's watching 'Dora (the Explorer)' and singing '(The) Wheels on the Bus' with Grandpa. She is smiling and laughing for family members. We're blown away by Lily's progress and so grateful to her rescuers,' Lily's family said, according to CNN.

Nobody knows exactly how the infant survived hanging upside down for nearly 14 hours in her car seat with no food or water.

As she dangled, icy water rushed just below her head through broken car windows as the Dodge Caliber sat perched on the bank and rocks. The temperatures were near freezing throughout the night and through the morning.

'It's heartbreaking. Was she crying most the night?' said Beddoes, a 30-year-old father of two. 'It's a miracle... She was needed for sure elsewhere.'

Car crash: Police believe that Lynn Groesbeck struck a cement barrier on a bridge before landing in the river upside down on Friday

Devastating: A fisherman found car the next day, partially submerged in the river. Groesbeck was found dead in driver's seat of vehicle, while her baby girl was alive in the back seat, above the frigid river waters

And that voice? Beddoes said he and the three officers talked later and concurred they all heard the same thing. They can't explain it, but have no doubt they heard it.

'That's the part that really sends me for a whirl,' Beddoes said. 'I'm not really religious, but that's what you think of.'

Police believe the accident occurred when the baby's mother, Lynn Groesbeck, struck a cement barrier on a bridge and careened into the river late Friday in Spanish Fork, about 50 miles south of Salt Lake City.

She was driving to her home in Springville after visiting her parents in Salem, Spanish Fork police Lt. Matt Johnson said.

A fisherman found the crashed car upside down in the river on Saturday at 12.30pm, about 14 hours after the accident occurred around 10.30pm on Friday.

A neighbor in the area reported hearing a loud noise near the bridge Friday night at about 11pm, but couldn't locate the cause of the sound after checking the area near Provo.

Investigators don't know what caused the crash, he said. There were no skid marks or signs of mechanical failures in the car.

Rescue mission: When Lily was retreived from the car, police officers handed the cold girl to one another until she reached the shore and emergency workers could rush her to the hospital

Aspiring dreams: Jill Sanderson, Lynn's sister, said Groesbeck was enrolled at Provo College with a goal of becoming a medical assistant, and had lived in the Provo area her entire life

Night drive: Police said that Lynn Groesbeck was driving home from her parents' house in Salem on Friday when the accident occurred

Unknown cause: Investigators are still unsure as to what caused the crash. There were no skid marks on the road and no signs of mechanical errors in the car

Police don't suspect drugs or alcohol as a factor but are awaiting toxicology test results. Maybe Lynn Groesbeck was tired or distracted, Johnson said, adding authorities weren't ruling anything out.

The child was first taken to Mountain View Hospital and then flown to Primary Children's Hospital in critical condition.

'She is doing remarkably well considering the circumstance. The doctors have been hopeful so far,' said Lynn's sister, Jill Sanderson on Sunday. 'We would like to express our appreciation to the Spanish Fork rescue team for saving the baby's life.'

Sanderson said her sister was enrolled at Provo College with a goal of becoming a medical assistant, and had lived in the Provo area her entire life, according to KSL.

Grosebeck was also the youngest of five children, including three brothers and her sister.

'She was very compassionate and a very loving person and always willing to bend over backwards for her loved ones,' said Sanderson. 'Her baby was the love of her life. She was an amazing mother.'

Mystery: A neighbor reported hearing a loud noise on Friday just after the car crash, but when they checked the area around Provo, no cause of sound could be located

Frigid: The waters of the river, just 50 miles outside Salt Lake City were near freezing. Multiple emergency responders were treated for hypothermia

Obstruction: Police said the car likely sat in the river for so long because the scene of the accident shielded by cement barriers on the side of the road

Groesbeck was enrolled at Provo College with a goal of becoming a medical assistant, her sister Jill Sanderson told the Deseret News.

Even though the road that goes over the bridge gets plenty of traffic, no one saw the wreck because the cement barrier obstructed the view of below, Johnson said.

If the fisherman didn't choose that river that morning, it could have been several more hours, he said.

Sanderson wasn't available for comment Monday but she told the Deseret News newspaper and KSL-TV of Salt Lake City on Sunday that Lily is doing remarkably well considering what happened.

Beddoes said the family has thanked him and the other officers for helping to save little Lily. As he recalls the events of those chaotic moments, on a frigid but sunny day, Beddoes still can't believe the girl survived — and still can't make sense of that undeniable voice coming from the car.

'We all got together and we all heard the same type of thing,' Beddoes said. 'We just can't grasp what we were hearing.'