Milan, Italy (CNN) -- About 150 people were missing Wednesday after a boat capsized in the Mediterranean Sea, the Italian Coast Guard said. The boat was carrying about 200 passengers when it sank about 39 miles (62 kilometers) west off the island of Lampedusa in Maltese waters, the Coast Guard said. Maltese authorities were heading the rescue operation with the Italian Coast Guard assisting. Darkness and poor weather hampered the search when the first rescue boats arrived early Wednesday morning, officials said. Since then, rescue vessels have rescued 48 people and were looking for the rest. The passengers are believed to be of Tunisian descent.
The boat was carrying 200 passengers, the Coast Guard says . 48 have been rescued . Poor weather hampers rescue efforts .