BANGKOK – Thai authorities declared a strict new state of emergency for the capital on Thursday, a day after a student-led protest against the country’s traditional establishment saw an extraordinary moment in which demonstrators heckled a royal motorcade.After the pre-dawn declaration, riot police moved in to clear out demonstrators who after a day of rallies and confrontation had gathered outside Prime Minister Prayuth Chan-ocha's office to push their demands, which include the former general's stepping down, constitutional changes and reform of the monarchy.Several top leaders of the protest movement were taken into custody, with one later declaring on his Facebook page that he had been denied access to a lawyer and was being forced onto.