A white police officer has been jailed for 15 years for murdering an unarmed, black 15-year-old boy in Dallas, Texas.

The verdict represents what is an extremely rare phenomenon - a murder conviction for a shooting involving on-duty police officer.

Roy Oliver was fired from his job with the Balch Springs Police Department in the days after the high-profile 2017 shooting of Jordan Edwards. He faced up to life in prison, and was sentenced on Wednesday night one day after being convicted for murder.

The court had heard how Jordan was killed while sat in the front passenger seat of a car packed with his friends as they left a house party in suburban Dallas.

Oliver and his partner had responded to reports of underage drinking at the party. When they arrived, Oliver fired into the car carrying Jordan and his friends, and later said he feared the vehicle was moving towards and endangering his partner.

Police initially said the vehicle reversed towards officers "in an aggressive manner", but later admitted that bodycam video showed the vehicle was moving forwards as the officers approached.

Oliver's partner told jurors he didn't ever believe his life was in danger, while investigators said no guns were found in the vehicle.

When the verdict was read Tuesday, gasps echoed around the courtroom. Jordan's relatives sobbed and hugged prosecutors, waved their hands in the air and proclaimed "Thank you, Jesus!"

"I just want to say I'm happy, very happy," Jordan's father, Odell Edwards, said outside the courtroom. He said it had "been a long time" since he felt that way.

The jury, which featured two black members out of 12 jurors and two alternates, acquitted Oliver on two lesser charges of aggravated assault stemming from the shooting.

It's extremely rare for police officers to be tried and convicted of murder for shootings that occurred while they are on duty. Only six non-federal police officers have been convicted of murder in such cases — and four of those convictions were overturned — since 2005, according to data compiled by criminologist and Bowling Green State University professor Phil Stinson.

Jordan's father has also filed a civil lawsuit in connection to the shooting.