Rescue ships fanned out Thursday in search of hundreds of migrants feared missing after their overcrowded boat capsized and sank as they tried to reach Europe. At least 78 people died.

So far, 104 people who were aboard the fishing boat traveling from Libya to Italy have been rescued, but authorities fear that many more may have been trapped below deck. If confirmed, that would make the tragedy one of the worst ever recorded in the central Mediterranean.

"The chances of finding (more survivors) are minimal," retired Greek coast guard admiral Nikos Spanos told state-run ERT television.

The U.N. migration agency, known as IOM, estimated that the vessel was carrying 700 to 750 people, including at least 40 children, based on interviews with survivors. Those rescued were mostly men and included Egyptians, Syrians, Pakistanis, Afghans and Palestinians, Greek officials said.

Authorities revised the confirmed death toll from 79 to 78 following an overnight count of the bodies, and rescue workers transferred the dead to refrigerated trucks.

"The survivors are in a very difficult situation. Right now they are in shock," Erasmia Roumana, head of a United Nations Refugee Agency delegation, told The Associated Press after meeting the rescued migrants in a storage hangar in the southern port of Kalamata.

MIGRANT FISHING VESSEL CAPSIZES OFF COAST OF GREECE KILLING AT LEAST 78, DOZENS STILL MISSING

"They want to get in touch with their families to tell them they are OK, and they keep asking about the missing. Many have friends and relatives unaccounted for."

Mohamed Abdi Marwan, who spoke by phone from Kobani, a Kurdish majority town in northeastern Syria, said that five of his relatives were on the boat, including one who 14 years old. Marwan said he’s heard nothing about his relatives since the vessel sank. He believes his nephew Ali Sheikhi, 29, is alive, after family members spotted him in photos of survivors, but Marwan said friends are still making their way to the makeshift camp in Greece to confirm.

"Those smugglers were supposed to only have 500 on the boat and now we hear there were 750. What is this? Are they cattle or humans? How can they do this?" Marwan said. He said that each of his relatives paid $6,000 for the trip.

Greece declared three days of mourning and politicians suspended campaigning for a general election on June 25. A Supreme Court prosecutor ordered an investigation into the circumstances of the deaths.

Survivors of a shipwreck react outside a warehouse at the port

Survivors of a shipwreck react outside a warehouse at the port in Kalamata town, about 150 miles southwest of Athens, on June 15, 2023.  (AP Photo/Thanassis Stavrakis)

Greek authorities said that the vessel appeared to be sailing normally until shortly before it sank, and declined repeated offers of rescue, while a network of activists said they received repeated distress calls from the vessel during the same time.

The Greek Coast Guard said that it was notified of the boat's presence late Tuesday morning, and observed by helicopter that it was "sailing on a steady course" at 6 p.m.

A little later, the Greek Joint Search and Rescue reached someone on the boat by satellite phone, who repeatedly said that passengers needed food and water but wanted to continue sailing to Italy.

GREECE ELECTION: ECONOMY, MIGRATION, SCANDALS LOOM LARGE IN PIVOTAL VOTE

Merchant and ships delivered supplies and observed the ship until early Wednesday morning, when the satellite phone user reported a problem with the engine. About 40 minutes after the engine trouble was reported, according to the coast guard statement, the migrant vessel suddenly began to rock violently and then sank.

Coast guard experts believe the boat may have sunk after running out of fuel or suffering engine trouble, with movement of passengers causing it to list and ultimately capsize.

Alarm Phone, a network of activists that provides a hotline for migrants in trouble, said that the trouble began much earlier in the day. The network said it was contacted by people on the vessel asking for help shortly after 3 p.m., who said "they cannot survive the night."

Around 6:20 p.m., Alarm Phone wrote, migrants reported the vessel was not moving and that the captain had abandoned the ship on a small boat, according to the group. The two accounts could not immediately be reconciled.

Experts said maritime law would have required Greek authorities to attempt a rescue if the boat was unsafe, whether or not passengers requested it. Search and rescue "is not a two way contract, you don’t need consent" retired Italian coast guard admiral Vittorio Alessandro told the AP.

An aerial photograph of the vessel before it sank released by Greek authorities showed people crammed on the deck. Most were not wearing life jackets.

Overcrowding, a lack of life vests, or the absence of a captain would have all been reasons to intervene, Alessandro said.

Greece’s caretaker minister in charge of civil protection, Evangelos Tournas, strongly defended the coast guard’s conduct and insisted that the migrants repeatedly refused assistance, insisting on continuing to Italy.

"The coast guard cannot intervene with a vessel which doesn’t accept the intervention in international waters," he said. "Consider also that an intervention by the coast guard could have placed an overloaded vessel in danger, which could capsize as a result of the intervention."

Twenty-nine of the survivors remain hospitalized in southern Greece, mostly with symptoms of hypothermia, while eight have been questioned by coast guard investigators. Government officials said the survivors would be moved to a migrant shelter near Athens later Thursday or Friday.

The bodies of the dead migrants were moved to a morgue outside Athens, where DNA samples and facial photographs will be taken to start the identification process. The embassies of the countries involved will assist, health officials said.

The location of the accident is close to the deepest part of the Mediterranean Sea, where depths of up to 17,000 feet (5,200 meters) could hamper any effort to locate a sunken vessel.

CLICK HERE TO GET THE FOX NEWS APP

Ursula von der Leyen, the European Commission president, said she was "deeply saddened" by the tragedy and promised to strengthen cooperation between the European Union and nearby countries to try to further crack down on migrant smugglers.

But human rights groups argue that the crackdown has forced migrants and refugees to take longer and more dangerous routes to reach safe countries.

The IOM has recorded more than 21,000 deaths and disappearances in the central Mediterranean since 2014.

The Mediterranean’s deadliest shipwreck in living memory occurred on April 18, 2015, when a fishing boat overcrowded with migrants collided off Libya with a freighter trying to come to its rescue. Only 28 people survived. Forensic experts concluded that there were originally 1,100 people on board.