Pakistan's national channel taken off air after protesters storm building

(Reuters) - Pakistan's national PTV channel and its English-language PTV World service were taken off the air after protesters stormed its headquarters in central Islamabad. "They have stormed the PTV office," a news anchor said just before the screen went blank. "PTV staff performing their journalistic duties are being beaten up." Another TV channel, Express, showed images from inside the building, with protesters, some wearing gas masks, massing inside the channel's newsroom but there were no signs of violence. (Reporting by Maria Golovnina and Syed Raza Hassan; Editing by Nick Macfie)