A 15-year-old boy in Hong Kong is in critical condition after undergoing emergency brain surgery on Wednesday night after a blow to his head, most likely the impact of a tear gas canister fired by the police. A 70-year-old man died after spending the night in intensive care for a head injury from a brick thrown during a street battle, while a man dressed in the black clothing favored by protesters fell to his death under unclear circumstances.

The Hong Kong Free Press reported on Thursday morning the 15-year-old boy remained in intensive care after four hours of surgery to repair his fractured skull at Tuen Mun hospital. Photos and video of the boy bleeding from the head have circulated online, but as yet there does not appear to be any footage of what injured him.

Local media outlets reported the boy was injured after protesters set up a roadblock and threw Molotov cocktails at the Tin Shui Wai police station. Police responded by firing tear gas into a crowd gathered at a nearby shopping center, evidently striking the 15-year-old in the head with one of their gas projectiles. It is not clear if he was one of the protesters or a bystander, although photos from the scene show him wearing black, the color favored by members of the protest movement.

There is online video footage of the 70-year-old man getting hit with a brick during a clash between pro- and anti-Beijing demonstrators. Reports described the man as a commercial cleaning subcontractor for the Food and Environmental Hygiene Department who was not a member of either group, but was caught in the crossfire as they heaved bricks at each other and brawled in the street.

Shortly before midnight local time on Thursday, the elderly man reportedly died from his injury.

The Hong Kong government blamed “masked rioters” who “conducted extremely dangerous and violent acts in various districts” and “wantonly assaulted other members of the public.”

“Police will resolutely take law enforcement actions to restore public order,” the government vowed.

A mysterious death in Kwai Chung on Wednesday night involved a black-clad man, about 30 years of age, plummeting from a building to his death on Kwai Fuk Road. An eyewitness reported seeing the man fall and break both arms on impact. He later died from his injuries in the hospital.

According to local media reports, a fire staircase in the building was unlocked and there are no security cameras covering the stairs, so the circumstances of the man’s death could not immediately be determined. No suicide note had been found as of Thursday morning.

The incident was disturbingly reminiscent of the death of Alex Chow Tsk-lok, a 22-year-old student who died last week from injuries sustained when he fell from a parking garage. The exact circumstances of Chow’s death are still unknown, but he is regarded as the first student casualty of the Hong Kong protest movement, and there was considerable public anger over his death.

A video circulating online Thursday showed a group of about a dozen masked men using metal rods to beat black-clad protesters, apparently not far from where the 70-year-old cleaner was hit with a brick. A witness overheard in the video remarked that the metal rods looked like the sort of collapsible batons carried by off-duty police officers. Uniformed police did not arrive on the scene until two hours after the first reported attack, a delay they blamed on road blockages created by protesters. The video is said to have inspired dozens of angry demonstrators to gather near the scene of the beatings.

Chinese state media continued pushing for a more forceful crackdown on protesters, running editorials that sneered at the United States and other outsiders for criticizing “police brutality” in Hong Kong when they have so many incidents of their own, advising against making any concessions to the protesters because that would only embolden them, and urging the authorities to forcibly reclaim university grounds from “subversives.”

“The black-clad rioters need to be reminded: Campuses can never be safe havens for criminals,” China Daily warned.