Jacob Steven Donn, 25, appeared via video link before Magistrate Howard at court on Thursday charged with a string of 14 charges.

The charges include: two counts of dangerous driving occasioning death-drive manner dangerous, negligent driving (occasioning death), negligent driving (occasioning grievous bodily harm), dangerous driving occasioning grievous bodily harm driving in a dangerous manner, two counts of cause bodily harm by misconduct in charge of motor vehicle, never licensed person driving a vehicle on road, two counts of fail to stop and assist after impact causing injury, two counts of failing to stop and assist after vehicle impact causing death, failing to stop and assist after vehicle impact causing grievous bodily harm, and possess a prohibited drug.

Donn made no application for bail on Thursday, and it was formally refused by the court.

He will appear again before Dubbo Local Court on January 12.

About 4.30pm on Tuesday emergency services were called to Warne Street in Wellington after a red Holden Commodore struck five people.

NSW Ambulance paramedics treated an adult and four children at the scene. Two of the children, boys aged six and seven died a short time later.

A 34-year-old woman was flown to Westmead Hospital where she remains in a stable condition.

A 10-year-old boy sustained serious leg injuries and was flown to the Children's Hospital at Westmead, where he remains and is undergoing surgery.

A nine-year-old boy sustained minor injuries and was taken to Orange Hospital. He has since been released.

Donn allegedly left the scene and was arrested by police later that evening around 8.40pm.

Orana Mid-Western Police District Acting Superintendent Natalie Antaw described the scene as "horrific" and "heartbreaking", and said their support was with the family and township of Wellington.

"It's tragic circumstances for the entire community and our thoughts are completely with the family and friends of the little ones involved, and also the rest of the community of Wellington," she said.

Acting Superintendent Antaw said the scene was particularly difficult for emergency services and locals to witness.

She described the actions by emergency services a "team effort" after reports a police officer drove an ambulance while paramedics worked on one of the patients.

"All of our officers will be taken care of and certainly it's one of those jobs where you sometimes wish your arms were a little bit longer so you can wrap them around all your staff," she said.

"We have liaison officers in contact with the family, obviously they're grief-stricken in relation to the tragedy and the loss of their children and we will be offering our assistance to them as well.

"We would be encouraging anybody who is feeling traumatised as a result of the incident to get in contact with their GP and seek medical help."