The Barbican Centre canceled all events scheduled for today, including a concert by Brazilian singer Daniela Mercury.

Also canceled were all events at the City of London Festival, including an organ recital at St. Paul's Cathedral and a performance of Bach's Musical Offering by Ton Koopman and the Soloists of the Amsterdam Baroque Orchestra at Haberdashers' Hall.

At the South Bank Centre, a recital by guitarist Julio Cesar Almeida, with music by Villa-Lobos, Bach, Piazzolla, Albeniz, and others, was postponed.

A performance by the winners of the Royal College of Music's Young String Player of the Year at Wigmore Hall was canceled. The event was to have featured a guest performance by violinist Victoria Goldsmith.

A concert by the London Symphony Orchestra's St. Luke's Community Choir and Children's Choir at the orchestra's music education venue was canceled.

Nearly all of the West End theaters also canceled tonight's performances. For more information, visit Playbill.com.

The explosions, in three subway tunnels and on a bus, started at 8:50 a.m. GMT and killed at least 33 people, according to the BBC; hundreds of people are said to have been injured. A previously unknown group calling itself the Secret Organisation Group of al-Qaeda of Jihad Organisation in Europe took responsibility for the blasts.

Most of the organizations said that they expected to return to their usual schedules tomorrow.