HONG KONG — Thousands of antigovernment demonstrators in Hong Kong dodged police tear gas and occupied a major shopping district and other central areas on Sunday, in the second of three straight days of large-scale civil disobedience.

The flash mob-style maneuvers came a day after violent street clashes erupted between protesters and riot police officers, resulting in more than 20 arrests, and a day before a planned citywide strike that may significantly disrupt daily life in Hong Kong, a semiautonomous Chinese region.

The long weekend of civil unrest — in which thousands of black-clad protesters have deliberately kept the authorities guessing their next move — may place a new level of pressure on Hong Kong’s deeply unpopular government to meet the protest movement’s broad range of demands.