Jurors were unable to reach a verdict Wednesday in the manslaughter trial of an officer charged in the death of Freddie Gray, and it's not yet clear if or when he may face another trial.

Five other officers also have been charged in the death of Gray, who suffered a severe spinal injury in the back of a police van after he was arrested in April. He died a week later. His death led to widespread unrest in the city, including some rioting, and the National Guard was called in to help restore order. The Justice Department has since launched a civil-rights investigation of the city's police department, and the city's already-high homicide rate has soared in the months since Gray died.

Here is a look at what has happened in the case:

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MISTRIAL

Judge Barry Williams declared a mistrial in the case Wednesday, a day after he told deadlocked jurors to keep trying for a verdict.

The judge told the jurors they had "clearly been diligent" before he dismissed them.

Gray died after suffering a broken neck in a police van while handcuffed and shackled. An autopsy concluded his head was probably slammed against inside the van as the van turned a corner or stopped.

The case hinged on what prosecutors said Officer William Porter failed to do: They said Porter should have called an ambulance when Gray indicated he needed medical help, and should have buckled Gray's seat belt. One prosecutor referred to the van as a "casket on wheels."

Porter testified Gray didn't seem hurt. He said he told the driver and a supervisor Gray wanted to go to a hospital.

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WHAT COULD HAPPEN NEXT?

Prosecutors have not indicated whether they will seek to retry Porter. State's Attorney Marilyn Mosby declined to comment on Wednesday's result, citing a gag order. The judge was scheduled to meet with prosecutors and defense attorneys in his chambers on Thursday to discuss a possible retrial date. There are several factors at play:

— Prosecutors could seek to try Porter again on all four charges he faces. They could also decline to pursue some or all of the charges.

— Prosecutors had indicated they wanted to try Porter first because they wanted him to testify against at least two of his colleagues. But the mistrial could complicate that strategy, and depending on how the other trials are scheduled, he may not be available to testify.

— Defense attorneys could seek again to have Porter's trial moved out of Baltimore. The hung jury reflects a deep divide among Baltimore residents about the officer's culpability and suggests that a fair trial in the city might not be possible, said Steve Levin, a city defense attorney and former federal prosecutor.

Officer Caesar Goodson, the driver of the police van in which Gray suffered a severe spinal injury, is scheduled to go on trial Jan. 6. He's charged with second-degree murder, the most serious charge in the case, along with manslaughter, assault and other offenses.

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WHAT'S HAPPENING IN BALTIMORE?

Demonstrators are gathering, and two have been arrested. Several protesters are marching through the city, chanting that they are seeking justice for Gray. But so far, everything appears to be peaceful.

Baltimore Police Commissioner Kevin Davis said police are out on the streets to serve as peacekeepers. He said protesters have "a friend" in the department, but people who commit crimes and hurt people lose their right to call themselves demonstrators.

Meanwhile, Gray's family has urged calm. Billy Murphy, who represents Gray's mother and stepfather, said he has every confidence Officer William Porter will be convicted if he is tried a second time. He said Gray's family is not angry and that they want people to remain calm, understand what happened and keep their emotions in check.