HONG KONG (AP) — Hong Kong residents are enduring a fourth day of traffic snarls and mass transit disruptions as protesters closed some major arteries and rail networks while police skirmished with militant students at major universities.

Life in this city of 7.5 million has been under strain as thousands of commuters were unable to make it to work and the government appealed on Thursday for employers to show flexibility.

Riot police fired tear gas during standoffs with students at Polytechnic University. Militant protesters have hurled gasoline bombs and thrown objects off bridges during clashes at university campuses this week. Chinese University suspended classes for the rest of the year, and others asked students to switch to online learning.

Pro-democracy protests have riven Hong Kong, and divided its people, for more than five months.