Taiwan stepped up security at transport hubs across the island after knife attacks in the capital killed three people and injured several others — a rare violent spree that shocked the democracy of 23 million people.Armed police were stationed at major subway stations in Taipei on Monday morning. Police were also sorting though a spate of reports of threatened copycat attacks, including one involving a bomb on the subway.For all the latest headlines, follow our Google News channel online or via the app.“We have received dozens of security threats since the incident occurred,” Lu Chun-hung, a Taipei police commander in the Criminal Investigation Division, told Bloomberg News by phone.Police would step up security at transport hubs, New Year’s celebrations, concerts and large activities, Lu said, adding that law enforcement would “strengthen police deployment and enhance on-site response mechanisms and capacity, and safeguard public safety.”The heightened focus on security comes after a