Italy was shaken over the weekend by the deaths of six young Egyptians who drowned while trying to swim 20 metres from a wooden fishing boat to the shore, and whose bodies were laid out in bags beside sun umbrellas on a popular Sicilian beach.

The prosecutor of Catania, Sicily's second city, opened an investigation after the boat, which had been carrying more than 100 migrants from Egypt and Syria, ran aground on a sandbar near the Lido Verde resort.

Roberto D'Arrigo, a spokesman for the Catania coast guard, told the Guardian that some of the passengers had jumped into the water to try to swim to safety, while others had remained on board.

Among the 98 survivors were about 50 minors, many of them small children, he said.

It was suspected that the six men who died, and who were identified on Sunday as Egyptians between 17 and 27 years old, may not have known how to swim. The Ansa news agency reported that the youngest was to have turned 18 this month.

According to the UN, about 8,400 migrants and asylum seekers landed on the coasts of Italy and Malta during the first six months of this year, many of them from Egypt, Syria and countries in sub-Saharan Africa.

It is rare, however, for boats to approach populated shorelines near Italian cities, and investigators were reported as saying they thought the vessel may have taken a wrong turn. At about the same time as the migrants arrived, so too did three large cruise ships carrying some 12,500 tourists keen to view Mount Etna from the port.

Police have arrested two Egyptians, aged 16 and 17, on suspicion of assisting illegal immigration, but are said to fear that the smugglers may have managed to flee from the boat.

The Catania prosecutor, Giovanni Salvi, is looking into possible charges of multiple manslaughter in relation to the disaster. He told the Catholic newspaper L'Avvenire that the fishing boat may have been towed most of the way by a larger ship and said he suspected links to an "organised network".

Separate investigations had already indicated that local crime organisations were involved in the people smuggling, he said.

D'Arrigo said coastguards had launched an emergency rescue attempt after receiving an alert via the police from the Lido Verde's owner, who had heard cries coming from the beach.

Rescuers transported those still on the boat back to land and pulled others out of the water, he added.

The resort's beach was closed after the deaths, and Catania's city council called a day of mourning for Wednesday, when the funerals may be held.

Speaking on Italian radio on Sunday, Italy's foreign minister, Emma Bonino, said there was no miracle solution to a phenomenon which often leads to fatalities off the country's coastline. At the end of last month, 31 people were feared to have died while trying to reach the island of Lampedusa, the destination for most migrants and asylum seekers from Africa and the Middle East.

"Whether it be a dream or illusion, these people risk ending up in the hands of real merchants of illusions or death," said Bonino.

"But we're talking about people who are fleeing because of hunger or war or a mixture of the two, and therefore there is no miracle solution."

Her words were echoed in the testimony of a survivor in Catania, who said he had decided to leave Syria because he was unable to finish his exams. Yahia Khaddam, 19, told La Repubblica he had paid $1,500 (£1,290) for the journey, which he felt he had no choice but to make.

"Either you fight or your flee," he was quoted as saying. "I had to risk death in order to live. I accepted the risk. I paid, and I'm alive."