Jo-Ann Thwaites, 60, was hit as she crossed Pittwater Road after grocery shopping with her son in Brookvale on Friday morning.

She was allegedly hit by a 36-year-old truck driver who didn't stop and left her lying on the road at the intersection of Pittwater Road and Condamine Street.

A second truck travelling close behind then ran over Ms Thwaites and dragged her under his Izuzu truck for about 600 metres, Fairfax Media has been told.

The second truck driver, a 57-year-old man, stopped as soon as he had realised what happened.

The first truck driver was tracked down to a Girraween business on Friday afternoon and arrested. His truck was also seized for forensic examination.

He has been charged with failing to stop and render aid after impact causing death and negligent driving occasioning death.

Fairfax Media has been told Ms Thwaites stepped out to cross the road on a green pedestrian light just after 9am.

The first truck was turning left at the same intersection and may not have seen her.

However, it's understood there was blood and markings on his truck that would have indicated to him later that someone had been hit.

The second truck driver also didn't see Ms Thwaites on the roadway as he turned the corner. He was taken to hospital for blood and alcohol testing and has not been charged.

A crime scene spanned hundreds of metres and caused Pittwater Road to be closed for much of Friday.

A witness, Martin Reay, said it was a horrific scene.

"I came out, it was quite a commotion and... [I] just saw a heap of groceries on the intersection there," he told Channel Seven.

Tragically, it is the second loss for Ms Thwaites' adult children who lost their father to suicide in 2013. He suffered PTSD after serving in the army for 40 years.

The truck driver was granted conditional bail to appear at Manly Local Court on June 15.