By Barbara Liston, Reuters ORLANDO, Florida, June 12 – A gunman killed 50 people and injured 53 in a massacre at a gay nightclub in the tourist hub of Orlando, Florida, early on Sunday, the city’s mayor and police said, in an attack U.S. authorities have described as a “terrorism incident.” Screenshot photo courtesy of orlandosentinel.com The shooter was identified as Omar S. Mateen, 29, a man that a senior FBI official said might have had leanings towards Islamic State militants. Officials cautioned that the Islamist tie required further investigation. The death toll given by Orlando Mayor Buddy Dyer to reporters made the attack the deadliest mass shooting in U.S. history, eclipsing the 2007 massacre at Virginia Tech University, which left 32 dead. A police officer working as a security guard inside the Pulse nightclub, that has been operating in downtown Orlando since 2004, exchanged fire with the suspect at [...]