It’s a case of he said, he said. The accounts of why a police officer fatally shot Michael Brown on a street in Ferguson, Missouri, this weekend couldn’t be more disparate.

One side says the teenager was surrendering, his hands in the air to show he was unarmed, when the officer opened fire. Authorities counter that Brown attacked the officer in his car and tried to take his gun.

The St. Louis suburb of 21,000 was wracked by violence overnight as protesters outraged over the 18-year-old’s fatal Saturday shooting faced off with police.

While there were reports that some demonstrations were peaceful — protesters held up their hands, as Brown reportedly did, and others demanded a fair inquiry, chanting, “No justice, no peace” — there were also reports of fires, looting, vandalism and attacks on police officers.

The dispute between distraught Ferguson residents and police isn’t likely to be settled soon, as several entities conduct investigations and the FBI reviews the matter.

One thing is sure, though: What police say was self-defense by the yet-to-be-named officer doesn’t jibe with the accounts of those who say they saw the encounter.

Here’s what CNN has learned:

Brown was spending the summer in the neighborhood with his grandmother, Desuirea Harris, she told CNN affiliate KMOV. She described him as “a good kid.”

Family members say he was a recent graduate of nearby Normandy High School and was going to begin classes at Vatterott College on Monday.

Brown and a friend were walking to Harris’ house, his mother and grandmother said, when a Ferguson police officer confronted them.

This is where the stories part ways.

Dorian Johnson told CNN affiliate KTVI that he and Brown were walking in the middle of the street, and the officer told them to use the sidewalk.

The two told the officer they were only a minute from their destination and that they’d soon be out of the street.

There was an exchange of words, witness Piaget Crenshaw told the station, and the officer exited his vehicle and fired a shot. Both teens ran, Crenshaw said.

Johnson told KTVI he hid behind a car, but Brown stopped after a second shot was fired. Brown held up his hands to show he wasn’t armed, Johnson and Crenshaw said, and the officer shot him twice.

“(The officer) shot again and once my friend felt that shot, he turned around and put his hands in the air,” Johnson told KMOV. “He started to get down and the officer still approached with his weapon drawn and fired several more shots.”

That Brown was unarmed seems undisputed — St. Louis County Police Chief Jon Belmar said every casing found at the scene was from the officer’s weapon — but he said in a Sunday news conference that Brown was not an innocent victim.

“The genesis of this was a physical confrontation,” said Belmar, adding Ferguson police asked his office to investigate the case.

Without revealing what led to the dispute, Belmar said the preliminary investigation showed that the Ferguson officer tried to exit his vehicle, but Brown pushed him back into the car, “where he physically assaulted the police officer” and struggled over the officer’s weapon, Belmar said.

A shot was fired inside the police car, and Brown was eventually shot about 35 feet away from the vehicle, Belmar said.

He didn’t explain how Brown got so far away from the car or whether he was surrendering. He said he was declining to disclose certain details because he didn’t want to “prejudice” the case.

The officer is on paid administrative leave. There’s no word on when authorities will identify him, but Belmar said he has been with the force six years and is “unaware of any other issues that he’s been involved in.”

He will be required to undergo two psychological evaluations before returning to duty, the chief said.

Meanwhile, Brown’s mother, Lesley McSpadden, didn’t need to know his identity to direct some pointed words at the man who shot the son she knew as a “gentle giant.”

“You’re not God. You don’t decide when you’re going to take somebody from here,” she told KSDK.