A man accused of killing a Blue Mountains man by deliberately running him down has been granted bail.

Kieran O'Connor, 33, faced court today over the death of a 34-year-old man on Hay Street at Bullaburra yesterday afternoon.

Police alleged O'Connor ran the man down outside his ex-girlfriend's house.

They say the victim had also had a relationship with the woman.

Emergency services arrived to find the man was already dead, pinned under the car.

Police arrested O'Connor and took him to hospital for drug and alcohol tests.

He was then charged overnight with manslaughter and negligent driving.

Today O'Connor was supported by his parents as he faced Katoomba Local Court.

Police told the court they had grave cocerns for the woman's safety and had recently ordered a restraining order against O'Connor, after the pair split up.

But the magistrate still granted bail, saying O'Connor was not a flight risk and had no criminal history.

Under strict conditions he will pay a $15,000 surety and be required to stay away from his ex-girlfriend.

The matter will return to court next month.

Earlier today Acting Superintendent Paul Glinn said a number of witnesses tried to help the man after he was hit.

"The investigation is in its early stage. There's a number of people to be spoken to today and probably over coming days," he said.

"Police have got the capacity with I guess other authorities that if further information comes to light which indicates that other types or more serious charges should be preferred, that's an option we've got at another time."

The fatal incident came just over an hour after a 78-year-old woman was killed walking at Earlwood, in Sydney's inner west.

Investigators believe the woman stepped out from between two parked cars and was hit by a van.

The van's 40-year-old driver was not injured and was taken to St George Hospital for mandatory drug and alcohol tests.

Police are also continuing to investigate a hit-and-run in the city's west at Fairfield on Sunday night.

Alarna Richardson, 23, was killed when a car hit the motorcycle that she was a passenger on.

The bike's 21-year-old driver was also seriously injured.

Detectives believe the car responsible is an early 1990s model Toyota Corolla, possibly maroon in colour.

They say the car will have significant front-end damage from its impact with the motorcycle.