Hundreds of uniformed school students, many wearing masks, formed human chains in districts across Hong Kong on Monday in support of anti-government protesters after another weekend of clashes in the Chinese-ruled city.

Metro stations reopened after some were closed Sunday amid sometimes violent confrontations, although the mood in the Asian financial hub remained tense.

Early Monday, before school started, rows of students and alumni joined hands chanting “Hong Kong people, add oil,” a phrase that has become a rallying cry of encouragement for the protest movement.