Beyoncé arrived at the 33rd annual MTV Video Music Awards on Sunday with her daughter Blue Ivy and four mothers who lost their sons in fatal police shootings.

The special guests—Lesley McSpadden-Head, mother of Michael Brown; Gwen Carr, mother of Eric Garner; Sybrina Fulton, mother of Trayvon Martin; and Wanda Johnson, mother of Oscar Grant—previously made an appearance in Beyoncé’s visuals for her latest album, Lemonade (with the exception of Johnson), which was nominated in several categories. It's final track, "Formation," won the night's top honor, Video of the Year.

Beyoncé is a strong supporter of the Black Lives Matter movement, which highlights the police killings of black people across the states; at the time of "Formation"s release, many claimed that the video was a veiled attack on law enforcement making the appearance of McSpadden-Head, Carr and Fulton more touching.

The sons of these women were killed by people who were armed; many have since used their deaths as an example of racism in policing in the US.

It was Martin's death that sparked the beginnings of the movement back in 2012 and just two years later, Brown's death fueled outrage and propelled the protests into a worldwide movement.