Michael Brown, the unarmed black teenager killed by a Missouri police officer was shot at least six times, including twice in the head, according to a private autopsy. But a forensic pathologist said it's unclear if Brown's arms were up at the time of the shooting.

Brown's family requested the private autopsy for the teen, who was shot and killed by a police officer on Aug. 9.

It is the second autopsy to be conducted on Brown. On Sunday, U.S. Attorney General Eric Holder ordered a third autopsy for the teen, citing the "extraordinary circumstances" surrounding the case.

Dr. Michael Baden, former New York City chief medical examiner, and Prof. Shawn Parcells, an assistant pathologist, conducted the private autopsy for the 18-year-old on Sunday.

Parcells confirmed the preliminary results to CTV News Channel on Monday. He said the autopsy shows that four shots hit Brown in his right arm, and two hit his head.

It was likely one of the two shots to Brown's head that killed the teen, Parcells said. The team also believes that the two shots to the head were the last shots that occurred.

The autopsy also suggests that all of the shots were to the front of Brown's body, and Brown's head was down at the time, he added.

"We don't know if that means he was rushing at the officer, or if he was giving up," he said. "But when those two shots occurred, it would be consistent with Michael Brown starting to fall towards the ground, and the shots coming in at the top of the head."

Unclear whether Brown's arms were up

At a news conference later Monday morning, Baden said that all of the gunshot wounds could have been survived, except for the final shot to the head.

Benjamin Crump, the lawyer representing Brown's family, said the autopsy results confirm witness accounts that Brown was shot multiple times.

Crump noted that Brown's family wanted a separate autopsy because they feared the results of an autopsy by the county might be biased.

Initial police reports said that there was a scuffle between Brown and the officer who shot him moments before the teen was killed. But witnesses said the teen had his hands in the air when the officer opened fire.

At the news conference, Parcells said it was unclear what position Brown's arms were in during the shooting.

He said a graze wound on Brown's arm could have occurred in a number of different ways: Brown could have had his back to the officer, or he could have been facing the officer with his hands in the air or in front of his face in a defensive position. "We don't know," he said.

Parcells stressed to CTV News Channel that it is still too soon to tell what happened the day Brown was killed.

The team still needs to examine Brown's clothing, get details from the police reconstruction of the crime scene, and review witness and officer statements, he said.

"Once we have a lot of those elements, and we've been able to review those, we will really be able to have a better understanding of what occurred, and be able to forensically put back together the pieces of the shooting," he said.

Brown's death has sparked days of protests in Ferguson, with residents taking to the streets, demanding justice for the teen. Several of the protests turned violent as police, some heavily armed, clashed with protesters.

There have also been incidents of looters vandalizing and stealing from local stores, and residents stepping in to protect the same shops.

Late Sunday, Missouri Gov. Jay Nixon ordered the National Guard to Ferguson to help restore order.

The officer who shot Brown has been identified as Darren Wilson. Wilson is a six-year police veteran who has no previous complaints against him. Since the shooting he has been put on paid administrative leave.

The U.S. Justice Department opened a civil rights investigation into the deadly shooting.

With files from The Associated Press