A police officer wearing a protective suit approaching a package delivered to the radio station in Jakarta, Indonesia yesterday where a “book bomb” addressed to a liberal Muslim leader exploded on Tuesday injuring four people. Police found no bombs in the parcel of documents but authorities had found a “book bomb” in another district in the capital addressed to an Indonesian rock star known for his songs protesting against religious extremism, the fourth such incident this week in a campaign apparently aimed at moderate Muslims and counter-terror officials.