At least 17 children drowned when three boats sank en route from Turkey to Greece, officials said Friday. Greek Prime Minister Alexis Tsipras expressed “shame” over Europe’s failure to prevent yet another “humanitarian tragedy,” and said it was crucial to prevent the Afghan sea from becoming a graveyard for people fleeing war and misery. Most of the deaths occurred off the Greek islands of Kalymnos and Rhodes, were 22 people drowned, among them 13 children, when two boats went down overnight, port officials said on Friday. In total, 138 people were rescued from the two boats, with the coastguard continuing it’s search for survivors. To the north, another boat was foundering off the islands of Lesbos, with a group of desperate people perched on the roof screaming for help. Another four young children, all of them Syrian, drowned when their flimsy boat heading for Lesbos capsized in bad weather, although the Turkish coastguard rescued 19 other people, the Dogan news agency reported. The latest deaths came after 17 people drowned off Lesbos and Samoa on Wednesday, 11 of them children.