An 18-year-old man was sentenced on Monday to life imprisonment for murdering a care worker caught in the crossfire of a "Wild West" shootout in a south London car park.

Polish-born Magda Pniewska, 26, died instantly after she was hit in the head by a stray bullet a few hundred yards from her home in New Cross last October.

She had been talking to her sister in Poland on her mobile phone as the shooting between two teenagers erupted in a car park opposite the care home where she worked.

Armel Gnango, then 17, had denied murder, attempted murder and possessing a gun to endanger life but was found guilty by an Old Bailey jury last month on all charges.

He had admitted having a prohibited weapon.

During sentencing at St Albans Crown Court on Monday Gnango was told he would have to serve at least 20 years before becoming eligible for parole.

He was also sentenced to 12 years for the attempted murder of the other teenager and to five years for possession of a firearm, both sentences to run concurrently.

Prosecutors said Gnango was criminally responsible for Pniewska's death even though he did not fire the bullet that killed her.

At his trial the jury had heard that the youths had pre-planned their fight because Gnango was owed money by his rival.

"In scenes reminiscent of the Wild West, Magda was to become the innocent victim of a gunfight by two young men who were total strangers to her," prosecutor Brian Altman had told the jury.

"She was caught in the cross-fire between two youths armed with handguns which they were willing to use in public. Each had a score to settle."

Police only had enough evidence to charge Gnango - who was born in the Ivory Coast and lived in Brixton, south London.