One day after sounding off against police brutality and the fatal shooting of Alton Sterling, San Francisco 49ers quarterback Colin Kaepernick hopped back on social media Thursday to voice his frustration about the death of Philando Castile, a black man who was shot by a police officer during a traffic stop in Minnesota.

“We are under attack!” Kaepernick wrote on Instagram. “It’s clear as Day! Less than 24 hrs later, another body in the street." In the post, the quarterback shared a portion of the graphic video that Castile’s girlfriend, Diamond Reynolds, recorded in the immediate moments following the fatal shooting.

Commenters flooded Kaepernick's post with a myriad of reactions, ranging from shared anger at the shooting to disappointment that the football player waded into social activism. His previous posts about #BlackLivesMatter and other police shootings have garnered a similarly divisive set of responses.

"Thank you for posting and spreading awareness," wrote Instagram user Samslote. "It's true and it's wrong and it's sad. Keep it up Kap, big respect. #BlackLivesMatter."

Most of the comments were positive, although a significant number criticized the 28-year-old Wisconsin native.

"Wow... Maybe you should just pay more attention to football...," wrote Instagram user KierstonCrouse. "Had you remained more qb than gq maybe the 9ers would have done better. So much respect lost."

The video recorded by Reynolds, which was originally broadcast using Facebook Live, has been shared hundreds of thousands of times. It shows Castile slumped in the front seat of his car, soaked in blood, while the officer who shot him stands with his weapon still drawn. His girlfriend’s 4-year-old daughter can be heard in the backseat of the car, while his girlfriend narrates what has since been called an "execution" by anti-brutality activists.

"Please, officer, don't tell me that you just did this to him," Reynolds says during the video. "You shot four bullets into him, sir. He was just getting his license and registration, sir."

We are under attack! It's clear as day! Less than 24 hrs later another body in the street! A video posted by colin kaepernick (@kaepernick7) on Jul 7, 2016 at 9:11am PDT

The St. Anthony officer, who sounds distressed, yells back at one point: "I told him not to reach for it. I told him to get his hand off it." He has not yet been identified by the police department.

Minnesota governor Mark Dayton has said that the officer's actions were "way in excess" for a traffic stop and has asked the White House to launch an independent federal investigation into the shooting.

President Barack Obama made a statement about the Louisiana and Minnesota shootings Thursday, in which he recognized the "vast majority" of police officers for their hard work but acknowledged systemic racism in police departments.

"When incidents like this occur, there's a big chunk of our fellow citizenry that feels as if because of the color of their skin, they are not being treated the same," Obama said. "And that hurts."