LONDON (Reuters) – Tens of thousands took to the streets of London on Sunday, rallying for a second day running to condemn police brutality after the killing of George Floyd in Minneapolis, some wearing face masks to protect against COVID-19 bearing the slogan “racism is a virus”.

On Saturday, thousands of protesters had gathered in central London in a demonstration that was peaceful but that ended with small numbers of people clashing with mounted police near Prime Minister Boris Johnson’s Downing Street residence.

London Police chief Cressida Dick said 27 officers had been injured in “shocking and completely unacceptable” assaults during anti-racism protests in central London this week, including 14 on Saturday. Two were seriously hurt and an officer who fell from her horse underwent surgery in hospital.

Both Dick and health minister Matt Hancock urged protesters not to gather in London again on Sunday, warning they risked spreading the coronavirus. But demonstrators ignored this to pack the road outside the U.S. Embassy on the south bank of the River Thames. Journalists on the scene estimated the crowds as numbering in the tens of thousands.

After an hour, the protesters began to march across the river in the direction of parliament, pausing on the bridge to take the knee and chant “justice, now”. Some gathered in Parliament Square while others massed outside Downing Street.

“Now is the time: we need to do something. We have become so complacent in the UK but the racism that killed George Floyd was born in the UK in terms of colonialism and white supremacy,” said 28-year-old Hermione Lake, who was holding a sign saying “white silence = violence”.

“We need to completely gut the system … We need massive reform, massive change,” she added.

There have been demonstrations around the world over police treatment of ethnic minorities, sparked by the death of Floyd, a black American, on May 25 in Minneapolis. A white police officer detaining him knelt on his neck for nearly nine minutes.

Sunday’s London protest was peaceful, with people clapping, taking to one knee, waving placards and chanting “George Floyd” and “the UK is not innocent”.

Footage posted on social media showed anti-racism demonstrators in Bristol in western England cheering as they tore down a statue of Edward Colston, a 17th century slave trader.

Police said 29 people were arrested during Saturday’s protest in London for offences including violent disorder and assault on emergency service workers.

Pauline Nandoo, 60, said she had been protesting about racism since the 1970s and the images of violence at the end of Saturday’s protest had not deterred her.

“There’s children of all ages and older adults here,” said Nandoo, who was with her brother and 13-year-old daughter. “They are going to experience what we have experienced and we have to try to make that not happen.”