PUCALLPA, Peru - An eerie silence fell over the people inside a Peruvian airliner when it suddenly lost altitude as if "something was pushing it down by force from above," a doctor aboard the flight recalls.

Seconds later, the TANS Airline Boeing 737-200 carrying Ronald Doneyre and 97 others crash-landed in a jungle swamp.

And Doneyre remembers the stench of burning flesh as he ran for help.

The cause of Tuesday's crash, which killed at least 37 people, remains under investigation. But survivors describe an uneventful flight that suddenly turned into a frantic struggle to stay alive.

Doneyre, 39, a trauma surgeon in Argentina, was returning to his boyhood home of Pucallpa for vacation.

"It was sunny in Lima when we took off. I was relaxed. It was a good flight," he told The Associated Press. "The pilot indicated the flight would take about 50 minutes. Everything was great until 10 minutes before landing."

At that point, he and other passengers said the pilot told them to buckle up for landing, and the crew warned about turbulence as the plane began shaking.

Diane Vivas, 43, from the Brooklyn borough of New York, told AP that she "knew something was going to go wrong" the moment she saw the sky outside her window turn black.

The plane then, terrifyingly, dropped altitude three times in succession.

"We started feeling the plane repeatedly descend very roughly," Doneyre said.

"There where no screams. There was nothing," he continued. "We were all so tense waiting when we felt the impact."

The airline has said wind shear probably forced the pilot to try an emergency landing and credited his actions for saving so many lives. But some aviation experts have suggested the pilot was flying too low in his final approach to the runway and was to blame for the disaster.

Officials will study both claims as they investigate the crash, which occurred a few miles from Pucallpa's airport.

Doneyre said flight attendant Paola Chu asked him to help her open a rear door. She is widely credited with helping save a dozen passengers.

"I give her a lot of credit because she stood her ground helping others. She was able to get to safety also," Vivas' husband, Gabriel, said.

Chu and another flight attendant were the only members of the six-member flight crew to survive.

Diane and Gabriel Vivas were visiting his Peruvian homeland with his older brother, Jose Leandro Vivas, who had also brought his three daughters.

They said they were the first ones to exit through plane's rear door.

Gabriel said as they trudged through thigh-deep mud, he spotted a baby boy, about a year old, on the ground.

"I don't know how the baby got there, but my brother was there so I told him to grab the girls and keep going," Gabriel Vivas said.

"Me and this other gentleman, I don't know his name, I know he was from Argentina, he picked up the baby and we tried to get to higher ground," Gabriel Vivas said, referring to Doneyre.

"He got stuck in the mud and then I grabbed the baby. Then he jumped in front of me to push away the thorns that were in our way," he said.

Doneyre said they switched off, handing the baby and pushing back thick, thorny brush, to reach higher ground.

Monica Glenn, a 27-year-old California native, told Peru's Canal N television that she and her Peruvian husband, William Zea, tried to exit the aircraft through a left side door but flames raced through the cabin. They escaped through the rear door into a driving rain and hail storm.

"I think in a way the rain helped because we were burned," she said.

Survivors said there were two explosions - the first at the front of the plane as people escaped out the back, and the second minutes later, obliterating the rear section of the aircraft.

Glenn, the Vivas family and Doneyre said they huddled around the baby to protect him from the rain and hail.

"My uncle told us, 'Let us pray,' and we were silent around the baby," said Joshelyn Vivas, 15. "Hail was coming down on us and we went into like a cocoon around the baby."

Doneyre said it was around that time that he went for help.

"I got to a cow pasture and there the smell of smoke reached me and the smell of burning flesh because the wind had changed direction," he said.

He said a local man pointed him toward Pucallpa four miles away and he ran down a dirt path to a road, where he found the driver of a taxi, which took him to a police post - and help.