HONG KONG — Students on Hong Kong’s university campuses erected roadblocks and gathered bricks in preparation for battle with the police on Wednesday, as residents navigated severe transit disruptions and office workers brawled with officers in the heart of the financial district.

This week’s disruptions are notable because they have strained the city’s infrastructure during ordinary workdays, forcing commuters to choose whether to venture outside and risk being caught up in clashes and tear gas. The protests started in June over an extradition bill that has since been withdrawn, and have morphed into broader demands for democracy and police accountability.

Schools and universities have become flash points. A day after young demonstrators staged a fiery standoff against the police on the fringes of a university campus, the Education Bureau said on Wednesday that it was up to parents whether to send their children to school — a move that angered two prominent teachers’ unions.

Here’s the latest on the Hong Kong protests.

Protesters barricade entrances of campuses.

Student demonstrators with umbrellas, masks, bricks and shields geared up on Wednesday at the Chinese University of Hong Kong, a campus that has become a focal point of the confrontation between the protesters and the police.

On Tuesday night, riot police officers fired dozens of rounds of tear gas at demonstrators there who set a giant blaze and threw gasoline bombs in a clash that lasted for hours and left dozens injured.

Protesters at other universities were also building barricades at campus entrances and digging up paving stones on Wednesday in preparation for a potential standoff with the police.

The activists say they are defending their campuses from police intrusion. The police assert that they have to stop demonstrators from blocking roads, throwing bricks or trying to disrupt rail services.

Since the protests began, the movement has been driven in large part by high school and university-age students. But until recently, campuses were a relative safe zone from violent clashes.

• John Lee, Hong Kong’s secretary for security, defended the police on Wednesday. Universities are not meant to be “breeding grounds for violence,” he told reporters. “If someone sees violence and does not stop it, then that person becomes an accomplice.”

• The Education Bureau said on Wednesday morning that it was up to parents whether their children attended school, and that schools should keep their campuses open regardless. The bureau’s statement immediately prompted criticism from unions on opposite sides of the city’s political spectrum.

• The Hong Kong Professional Teachers’ Union, which has long supported the city’s pro-democracy politicians, condemned the city’s embattled leader, Carrie Lam, for having endangered teachers’ and students’ safety by not canceling classes entirely.

• And a pro-government teachers’ union, the Hong Kong Federation of Education Workers, said in a separate statement that while it strongly condemned “rioters” for depriving the rights of students to learn, it regretted the government had put schools in a difficult position by forcing them to remain open.

• The education bureau later said that all classes at Hong Kong kindergartens, primary and secondary schools would be suspended on Thursday.

Clashes erupt in financial district.

Large groups of riot police officers disrupted a rally in the city’s financial district around lunchtime on Wednesday, making multiple arrests and beating protesters with batons.

Many of the protesters were there to support the students who had been battling the police at the Chinese University of Hong Kong on Tuesday night. Office workers in suits and ties formed a human supply chain to move water and umbrellas to the front-line protesters.

“The Chinese University students suffered yesterday, come join us,” some of them chanted at bystanders.

When the police swooped in and started beating protesters, the crowd fought back, and a brawl erupted outside a luxury mall that houses an Apple store.

By early afternoon, the streets around the mall had the feel of a militarized zone, and were deserted except for a handful of officers, workers and tourists taking pictures. Some among a crowd of people in office attire started heckling the riot officers, calling them gangsters, driving the police to retreat.

Mainland students are leaving Hong Kong.

• The Hong Kong police said on Wednesday that some of the city’s marine police officers had been deployed to help evacuate mainland Chinese students who are attending the Chinese University.

• News of the evacuations prompted biting criticism of the Hong Kong Police on social media. Some users said it was hypocritical for the force to support mainland students while waging violence against local ones.

• China’s Communist Youth League, the youth division of the ruling Communist Party, offered the students seven days of free accommodation at its lodgings in Shenzhen, a mainland Chinese city that lies just over the border from Hong Kong. The group, in a social media post, touted the lodgings as a “comfortable environment” and a “welcoming place to set foot in Shenzhen.”

Young protesters’ grievances run deep.

• The protesters who clashed with the police outside the Chinese University of Hong Kong on Tuesday were angry over the police shooting of a young demonstrator at point-blank range on a street corner a day earlier. (He was in serious condition as of Tuesday.)

• Tensions had been building after the death last week of a student who fell from a parking garage amid demonstrations. Many in the protest movement now see the student, Chow Tsz-lok, as a martyr.

• Hong Kong’s youth are angry over what they see as a steady erosion of civil liberties under Chinese rule as well as the city’s sky-high cost of living. They also fear that their city’s unique culture and identity will be gradually subsumed by growing mainland Chinese influence.

The morning commute is disrupted, again.

There were widespread transit disruptions across the Asian financial center on Wednesday, marking the third straight day that protesters had impeded some of the city’s essential infrastructure.

Tiffany May, Keith Bradsher, Ezra Cheung and Austin Ramzy contributed reporting.