The gunman who massacred dozens in Las Vegas researched possible attack locations in Boston and Chicago, multiple senior law enforcement officials briefed on the investigation told NBC News.
Stephen Paddock's potential targets included the most recent Lollapalooza festival in Chicago, which was held August 3 to August 6 in Grant Park, the officials said.
Paddock went as far as booking a room in a Chicago hotel but did not show up, the officials said.
Police said Stephen Paddock, a 64-year-old resident of Mesquite, Nevada, opened fire on a music festival crowd from the 32nd floor of the Mandalay Bay Resort and Casino, killing at least 59 people and injuring over 500.
