An Ethiopian airliner carrying 92 passengers and crew crashed into the sea shortly after taking off from Beirut airport early Monday, an airport official said.
The official told the German News Agency dpa that around 50 Lebanese nationals were among the passengers. There were also seven crew members on board, he added.
The Boeing aircraft was en route to Addis Ababa, Ethiopia, when it disappeared off the radar screens shortly after take-off, the state-run Lebanese National News Agency (NNA) reported.
The plane departed at 1:46 am (2346 GMT Sunday) from Rafik Hariri International Airport in Beirut, according to the airport's flight schedule.
The airport official said the Ethiopian Airlines plane was struck by lightening before into fell into the sea between the areas of Khaldeh and Saadiyat about 15 kilometres south of Beirut.
Witnesses in the area said they heard a loud noise and then saw a plane on fire plunging into the water.
Rescue teams were seen gathering near the area where the plane reportedly crashed.
A member of the rescue team told dpa, "the weather is not helping us at all ... but we hope to find some survivors."
Rafik Hariri International Airport at the outskirts of Beirut was already packed with families who came to ask about the fate of their loved ones.
A lot of Ethiopian nationals work as domestic helpers in Lebanon.
Ethiopian Airlines operates a fleet of 37 predominately Boeing planes, according to its website.
The carrier has not suffered a fatal crash since November 1996, when 125 people died during a hijacking onboard a Boeing 767 bound for Abidjan, Ivory Coast.