Updated

State investigators looking into the death of an unarmed black Minneapolis man shot by police during a scuffle are trying to determine whether he was restrained at the time, as some witnesses allege.

Police initially said Jamar ONeal Clark was not handcuffed when he was shot, but authorities later said handcuffs were at the scene and that they are trying to determine whether Clark was restrained.

"We're still examining whether or not they were on Mr. Clark or whether or not they were just (fallen) at the scene. That's what we're trying to ascertain," state Bureau of Criminal Apprehension Superintendent Drew Evans said at a news conference Tuesday.

Clark, 24, died Monday, a day after police shot him during an early morning dispute. Police said the incident began when they were called to north Minneapolis around 12:45 a.m. Sunday following a report of an assault. When they arrived, a man was interfering with paramedics who were helping the victim, police said. Officers tried to calm him, but there was a struggle. An officer fired at least once, hitting the man, police said.

The head of the Minneapolis police union, Bob Kroll, said on Wednesday that the officers were interviewed Tuesday night.

"I hope they expedite the situation and wrap it up," Kroll said.

The shooting sparked protests, including one Monday night in which hundreds of people blocked traffic on an interstate highway, leading to 42 arrests. A nationwide movement -- Black Lives Matter -- spawned by the killing of black 18-year-old Michael Brown in the St. Louis suburb of Ferguson last year has demanded an end to police killings and the use of excessive force against unarmed black suspects.

Evans said investigators have video from several sources, including an ambulance, a mobile police camera stationed in the area, public housing cameras and citizens' cellphones. But he said none of the videos captured the entire incident and none will be released while the investigation is ongoing to avoid possibly tainting it.

Asked whether any of the video shows Clark in handcuffs, Department of Public Safety spokesman Bruce Gordon reiterated that it captures a portion of the incident, but not everything, and said officials can't discuss specifics because it could potentially taint witness statements.

Kroll said he hoped people who say Clark was handcuffed "make a statement to the BCA on that matter."

He added: "If it turns out to be blatantly false, they should be charged with a crime."

Pressed on the timeline for results of the BCA investigation, Evans said two to four months is typical but that the Clark case "has been given top priority."

The FBI also has agreed to conduct a civil rights investigation into the shooting.

Authorities have identified two Minneapolis police officers involved in the weekend shooting as Mike Ringgenberg and Dustin Schwarze. The state agency says both have been police officers for seven years, including 13 months with the Minneapolis department.

Authorities have said the officers involved weren't wearing body cameras. Evans said there is no police dashcam video of the shooting.

The Hennepin County Medical Examiner's Office ruled Tuesday that Clark died from a gunshot wound to the head. Clark's father previously told The Associated Press that his son was shot over his left eye.

Clark's brother, Jamine Robinson, 32, of Rochester, told the AP that family members went to the hospital Monday evening to take Clark off life support. He said he didn't go because he didn't want to see his brother in a hospital bed.

"I want the officer to be arrested, prosecuted and put in jail for eternity. Life without parole," said Robinson.

Protesters have set up tents around the 4th Precinct station near where the shooting occurred and said they won't leave until authorities release any video they have of the incident along with the identities of the officers involved.

The protests are just the latest expression of tension between the department and minorities in the city.

The rocky relations have led to discussions between police and minorities and the creation of task forces designed to quell concerns. This spring, Minneapolis was selected for a U.S. Justice Department program to rebuild trust between police and the communities they patrol.

The Associated Press contributed to this report