CNN) -- Hundreds of desperate passengers are enduring freezing conditions on a stricken ferry that has been burning in the Adriatic Sea for 24 hours. Helicopters have been working through the night to pull them off, one by one.
Passengers are "dying of cold and suffocating from the smoke," one Greek man told Italian state broadcaster RAI TV, describing how passengers' feet were "burning" from the heat of the flames. The fire is believed to have started deep in the ship's parking bay.
In the early hours of Monday morning, the Italian Coast Guard announced that 251 people had been rescued from the Norman Atlantic, which had been traveling between the Greek port of Igoumenitsa and the Italian port of Ancona when fire broke out on Sunday morning.
Authorities said 227 remained on board, including the captain, who was helping to coordinate the rescues.
Ferry catches fire between Greece, Italy
First images from inside burning ferry
Hundreds aboard ferry burning in Adriatic
One man died after he jumped or fell into the cold and rough water. Other passengers were suffering hypothermia in the freezing temperatures, worsened by the spray of tugboat hoses as authorities attempted to douse the flames.
Dramatic cell phone images filmed by a passenger showed flames through shattered portholes, while a wider view released by rescuers showed a huge plume of thick, black smoke streaming from the stricken vessel.
In the first three hours of the blaze, around 150 people were able to escape via the vessel's lifeboats. But when the ferry lost power, the electronic arms were unable to function, leaving the boats dangling uselessly by its side.
Many passengers were also unable to reach the lower decks because of the heat, and the water below was so cold that jumping clear of the ferry was not an option.
Passengers able to escape the ferry told Greek and Italian newsgroups they felt like "prisoners on a burning ship."
The Italian Navy said medical personnel were lowered onto the vessel early Monday, amid reports some passengers were suffering from smoke inhalation and hypothermia.
Hours earlier, a tugboat was attached to the ferry in an effort to hold it steady while helicopter pilots worked to shuttle passengers onto nearby merchant vessels.
A freighter carrying 49 rescued passengers was expected to arrive in Brindisi, Italy, near the port of Bari, the Italian Coast Guard said Monday. Passengers needing medical attention would be taken to nearby hospitals.
Fire spread quickly
It's not known how the fire started, but it's believed to have originated in the parking bay. At least one truck driver told the Greek news media that trucks filled with oil were "packed like sardines," their cargo scraping the ceiling, which could have set off sparks in rough seas to start a fire, he surmised.
Greek authorities said the vessel's fire doors appeared to have failed which allowed the flames to spread quickly.
The disaster made national headlines in Greece, Italy and other countries with citizens aboard the ferry. In a Sunday morning public address, Pope Francis offered "affection and prayers" to those affected by the Norman Atlantic ferry fire as well as a collision in the Adriatic Sea between two merchant ships.
Thick clouds of smoke enveloped the vessel earlier Sunday as rescuers awaited an opportunity to approach. At least eight ships were deployed, but heavy winds and freezing waters kept them at bay, making evacuation by air the only feasible option.
Turkish diplomatic personnel are heading to Igoumenitsa, the likely port for evacuated passengers, according to a Turkish Foreign Ministry statement released Sunday. Turkish citizens were among the passengers, with Greeks and Italians making up the majority.