Lebanon: New Qana massacre -- 40 killed sheltering in basement

More than 40 people, including 20 children, have been killed in an  Israeli air strike on the southern Lebanese town of Qana.  Displaced families had been sheltering in the basement of a site which was crushed after a direct hit.
The US secretary of state has cancelled a visit to Lebanon as its prime minister says he will only discuss a full and immediate ceasefire.
Hundreds of protesters are staging a violent demonstration in Beirut.
An angry crowd is attacking the UN building, chanting slogans against the US and in support of Hezbollah.