Kaylib Connolly, 18, was arrested yesterday (Sunday, November 24) on suspicion of murder following the death of Alison McBlaine.
Ms McBlain, 36, died in hospital on Thursday afternoon (November 21) with her family, including her 12-year-old son Reagan, at her bedside.
She was fatally injured after a Fiat Punto Grande deliberately mounted the pavement in Whalley Banks, at the junction with Pearson Street, at 7.45pm on Tuesday, November 19.
Dean Qayum, 20, (pictured) remains wanted in connection with Miss McBlaine's death.
A second pedestrian, a man aged 26 from Blackburn, also sustained serious injuries in the collision.
The car failed to stop at the scene and was later found abandoned on Lower Hollin Bank Street with significant front end damage.
Police said attempts had been made to set the vehicle on fire.
Three people were initially arrested by police on suspicion of murder.
A 26-year-old man and a second person remain in custody, with a 25-year-old man bailed to December 19.
Detectives are continuing to appeal for information about Qayum in connection with Miss McBlaine’s death and are warning anyone hiding him will be arrested.
Qayum is believed to have a leg injury and could be using crutches.
"Police want to speak to him and I believe they he is being harboured in and around the Blackburn area at this time.
"I would warn anyone who is protecting him, or helping to hide him, that we will identify this during our investigation and they will also be arrested and prosecuted.
"My thoughts and those of the team engaged on this inquiry remain with Alison’s loved ones, in particular her 12-year-old son Reagan. I would urge anyone with information about what has happened, or knows where Qayum is, to do the right thing – please come forward and speak to police immediately.
"I would urge the public to help us find those responsible for this brutal and callous attack."
Anyone with information should contact police on 101 quoting log 0915 of November 20th or through the Major Incident Portal at https://mipp.police.uk/operation/0401020119E09-PO1
You can also contact independent charity Crimestoppers on 0800 555 111 anonymously.