Rapper Eminem released a surprise album Friday, Music to be Murdered By, with a song entitled "Darkness," which is a direct rebuke of the nation's gun laws.

The song's music video, also released without warning, depicted a shooting at a concert, with lyrics that repeatedly alluded to the 2017 Las Vegas music festival shooting that left 58 people dead.

The video ended with multiple clips of news coverage from mass shootings and a text overlay calling for viewers to register to vote.

“When will this end? When enough people care,” read the text at the end of the video. “Register to vote at vote.gov. Make your voice heard and help change gun laws in America.”

A link to the video from Eminem's website also encouraged fans to contact gun violence prevention organizations, such as Everytown for Gun Safety and Sandy Hook Promise

In addition to the video's release, gun violence prevention groups across the country, like the Brady Campaign to Prevent Gun Violence, are complaining that the issue is not being mentioned enough on the Democratic debate stage.

"It’s disappointing that there was little substantive discussion of the gun violence epidemic in the United States. Gun violence affects every community and every voter," Brady Campaign President Kris Brown said in a statement. "Our nation’s failure to address this issue cuts to the heart of our democracy. We needed to hear solutions from those seeking the highest office in the country.”

The song's timing closely follows the formation of March for Our Lives, a movement led largely by survivors of the Parkland, Florida, school shooting. The movement's encouragement of youth participation and activism has been credited by some for Democratic gains in the 2018 midterms.