Image copyright Reuters Image caption Michael Rosfeld was acquitted after fewer than four hours of deliberations

A Pennsylvania court has acquitted a white police officer who fatally shot an unarmed 17-year-old black teenager in the back.

Michael Rosfeld, 30, shot 17-year-old Antwon Rose three times as he tried to flee police last June - just 90 minutes after the officer had been sworn in for duty.

He was charged with criminal homicide last year.

But the jury fully acquitted the officer on the fourth day of the trial.

They took fewer than four hours to make their decision.

Mr Rosfeld's lawyer, Patrick Thomassey, told reporters his client was "a good man", and said he hoped "everybody takes a deep breath and gets on with their lives".

Broadcaster WPXI says six to eight shots were fired into the lawyer's office on Friday night after the ruling. Nobody was hurt.

S Lee Merrit, lawyer for Rose's family, said the victim's mother "didn't really expect a different verdict" in light of rulings in similar cases elsewhere in the US.

Pittsburgh district attorney Stephen Zappala Jr said he disagreed with the court's decision.

In the wake of the verdict about 100 protesters reportedly blocked roads and read a poem written by Rose, while chanting his age.

The death of Antwon Rose is one of many high-profile cases of unarmed black men dying at the hands of white US police officers - cases that have ignited protests and civil unrest across the country.

What happened to Antwon Rose?

Officers stopped Rose's car because it matched the description of one sought in connection with a nearby shooting, police said. Rose was a passenger in the vehicle at the time.

Image copyright Antwon Rose/Facebook Image caption Antwon Rose, 17, was fatally shot three times as he fled police

When the driver was stopped and ordered out of the car, Rose and a second unidentified passenger ran away.

Rose was shot several times in the arm, face and abdomen from behind. He later died in hospital from his injuries.

The officers were not wearing body cameras at the time, but a video filmed by a bystander went viral and led to days of protests in Pittsburgh.

Media playback is unsupported on your device Media caption Video shows Antwon Rose being shot by police while running away

According to the criminal complaint, Mr Rosfeld first said he "saw something dark that he perceived as a gun," but witnesses said Rose had nothing in his hands.

Mr Rosfeld later changed his story, according to the detectives' complaint, saying he did not see a gun.