A Black Lives Matter rally brought parts of London's Oxford Street to a standstill today as hundreds gathered seeking justice for Philando Castile and Alton Sterling, the two black American men killed by police this week.

Demonstrators chanted, "Hands up, don't shoot," and "No racist police," as the crowd moved along Oxford Street to the U.S. Embassy on nearby Grosvenor Square and then back onto Oxford Street again.

Many brandished placards with messages like, "Life is not a white privilege," "All black lives matter," and "Solidarity with the families." Some sang an old Michael Jackson chorus, "All I want to say is that they don't really care about us."

Whenever a London bus driver honked a horn in support, the loud and peaceful crowd responded with an approving cheer. At one point, many demonstrators sat down on the world-famous shopping street while organisers decided which route the rally would take next.

Lorraine Oclaa, a 24-year-old protester from south-east London, told Refinery29 that today's protest was designed to highlight "an important issue that doesn't just affect people in America; it affects people all over the world - and not just Black people."

"Any person of colour is affected," she continued. "Look around, there's people of all ethnicities here. We're all here to let people know that our lives matter, and we've basically shut down Oxford Street, it's incredible."