State of emergency in Beirut

A state of emergency has been declared in Beirut after Tuesday's devastating blast. We get the latest from the city, speaking to a doctor in one of its hospitals and taking a walk around the ruined streets.

Also in the programme: on the 75th anniversary of the nuclear bombing that destroyed Hiroshima, we hear from one of its survivors, Keiko Ogura. And a look at the dilemmas faced by the big social media companies over freedom of speech and politics.

(Photo: A man takes photographs at the site of Tuesday's blast in Beirut's port area. Credit: REUTERS/Aziz Taher)