The Chinese and Hong Kong governments condemned on Friday an attack by a “violent mob” on the city’s justice secretary in London, the first direct altercation between demonstrators and a government minister during months of often violent protests.

Secretary for Justice Teresa Cheng, who was in London to promote Hong Kong as a dispute resolution and deal-making hub, was targeted by a group of protesters who shouted “murderer” and “shameful”.

A statement by the Hong Kong government said Cheng suffered “serious bodily harm” but gave no details.

The Chinese embassy in the UK said Cheng was pushed to the ground and sustained a hand injury.

“(Cheng) was besieged and attacked by dozens of anti-China and pro-independence activists,” the Chinese embassy said in a statement. The incident showed that the “violent and lawless perpetrators” were now taking their violence abroad, it said.

China has lodged a formal complaint with Britain and urged British authorities to bring the perpetrators to justice.

Hong Kong’s leader Carrie Lam also strongly condemned the attack.

The former British colony’s government said in a separate statement: “The secretary denounces all forms of violence and radicalism depriving others’ legitimate rights in the pretext of pursuing their political ideals, which would never be in the interest of Hong Kong and any civilized society.”

The incident came amid escalating violence in Chinese-ruled Hong Kong, where a student protester died earlier this month after falling from a parking lot during demonstrations.

A 70-year-old street cleaner, who videos on social media showed had been hit in the head by a brick thrown by “masked rioters”, died on Thursday, authorities said.

The Food and Environmental Hygiene Department expressed profound sadness on Friday at the death of its worker and said it was providing assistance to his family.

Anti-government protesters paralyzed parts of Hong Kong for a fifth day on Friday, forcing schools to close and blocking some highways as students built barricades in university campuses and authorities struggled to tame the violence.

Protesters used barriers and other debris to block the Cross-Harbour Tunnel that links Hong Kong island to Kowloon district, leading to severe traffic congestion. The government once again urged employers to adopt flexible working arrangements amid the chaos.

The protests escalated in June over a now-scrapped extradition bill that would have allowed people to be sent to mainland China for trial. They have since evolved into calls for greater democracy, among other demands.

Cheng, the embattled Lam’s chief legal adviser, played a key role in pushing forward the proposed extradition bill that ignited the protests.

The months-long protests have plunged Hong Kong into its biggest political crisis in decades and pose the gravest popular challenge to Chinese President Xi Jinping since he came to power in 2012. Xi said in Brazil on Thursday stopping violence was the most urgent task for Hong Kong.