All four police officers in the killing of George Floyd now will face charges, Minnesota Sen. Amy Klobuchar said Wednesday.

"Minnesota Attorney General Keith Ellison is increasing charges against Derek Chauvin to 2nd degree in George Floyd’s murder and also charging other 3 officers. This is another important step for justice," the Democratic senator tweeted.

Floyd family attorney Benjamin Crump earlier Wednesday implored officials to hold the officers accountable in powerful remarks at the site of Floyd's killing outside of a convenience store.

The incident has sparked mass protests over questions of police brutality and racial inequality and has shaken the nation. Once news of the additional charges broke, Crump called the moment "bittersweet" and said the Floyd family was "deeply gratified" for Ellison's action.

"This is a significant step forward on the road to justice, and we are gratified that this important action was brought before George Floyd’s body was laid to rest," Crump said in a statement. "That is a source of peace for George’s family in this painful time. Attorney General Ellison has informed the family that his office will continue to investigate and will upgrade the charges to first-degree murder if the evidence supports it."

Crump thanked people nationwide but pleaded for calm on city streets.

"We are deeply grateful for the outpouring of support by Americans in cities across the country, and we urge them to raise their voices for change in peaceful ways. Our message to them is: Find constructive and positive ways to keep the focus and pressure on. Don’t let up on your demand for change," he said.

Floyd was a 46-year-old black man who was killed Memorial Day after white Minneapolis police officer Chauvin knelt on his neck for more than eight minutes. Bystanders recorded video of the incident and shared it on social media channels. Once it went viral, it triggered an outpouring of outrage.

Chauvin and Thomas Lane, J.A. Keung, and Tou Thao were fired the day after the incident.

While Chauvin pinned down Floyd, the three other officers at the scene were recorded standing by and failed to intervene. 

Both the Hennepin County Medical Examiner's office and an autopsy commissioned by Floyd's family have ruled that Floyd's death was a homicide, though the reports disagreed on the cause.

The medical examiner's report released Monday listed "cardiopulmonary arrest” as the cause, while the family autopsy listed "asphyxiation from sustained pressure."

Who has been charged in George Floyd's death?

Chauvin was arrested and taken into custody May 29 and will now face second-degree murder and manslaughter charges. Crump has continued to call for the charge on Chauvin to be elevated to first-degree murder.

Lane, Keung, and Thao will also be charged, Klobuchar said.

When is Derek Chauvin due in court?

According to CNN, Chauvin is scheduled to appear in court on Monday.