A lone "gunman" being subdued by police officers in a terror attack simulation here yesterday morning. This was the second scenario in the annual anti-terror exercise codenamed Exercise Heartbeat. Office workers were evacuated from HSBC Building to the nearby Esplanade Park because of a suspicious vehicle. But the lone "terrorist", armed with a gun, anticipated the evacuation and planted a "bomb" at the park instead. A "hostage situation" then developed before Singapore Police Force and Singapore Civil Defence Force personnel stepped in.