The director of Chabad-Lubavitch, Rabbi Gavriel Holtzberg, and his wife Rivika are suspected to be among those being held hostage at its office in Nariman House, Colaba in South Mumbai, by terrorists since Wednesday night.

One terrorist has been killed and four others remain inside with the hostages, the Jerusalem Post has reported.

On Thursday morning the terrorists released the couple's young son and his nanny, who reported that the rabbi and his wife were alive but unconscious.

'Pray that we should hear good news,' Chabad spokesperson Rabbi Zalman Shmotkin told Jerusalem Post.

Joshua Runyan, news editor of Chabad's web site told the Jerusalem Post that a friend of the rabbi received an email from Holtzberg around the time of the attack, but unrelated to it, but there has been no contact with him since then. 'We've been trying all the numbers,' he told the newspaper.