At least 24 people, including ten children, drowned on Thursday after a boat carrying migrants from Turkey to Greece capsized near the island of Samos, the Greek coast guard said as it continued the search for an unknown number of others."It is horrible," a member of the Greek coast guard told dpa.It was unclear how many people were aboard. The circumstances of Thursday's sinking were unclear. The Greek coast guard and vessels from the European border patrol agency Frontex were carrying out a search and rescue operation off the island of Samos. Ten people were rescued, while 12 bodies those eight children, three men and one woman were recovered, other reports said.The sinking is the second in two days. Another boat sank off the island of Kos on Wednesday, leaving seven dead, including two children.Greece, with thousands of kilometres (miles) of coastline and islands very near the Turkish coast, is the main gateway into Europe for refugees.EU countries have been increasingly critical of Athens' handling of the continent's worst migration crisis since World War Two. More than a million migrants reached Europe last year, mainly through Greece.On Wednesday, the European Commission warned Greece it could face more border controls with other states in the free-travel Schengen zone from May if it does not fix "serious deficiencies" in its management of the area's external frontier.