The NSW Hunter region hotel worker was on his way home from a night shift at 3.45am when the bus he was travelling on left the road and flipped, landing in a creek bed on Wommara Avenue in Newcastle.

"I was playing a game on my phone, when it felt like we hit a pothole," the 24-year-old man said.

"There was a whole lot of rumbling and crashing and the bus just flipped. I was sitting in front of the back doors and I went over the metal railing. The guy who was sitting at the back of the bus was across from me and we just looked at each other like 'what the f***'."

The bus had been travelling westbound when it hit a concrete wall and overturned. According to nearby residents the crash made a "big bang" like a "bomb going off".

Mr Hayward-Powell said what followed the crash was confusion. Two people had been ejected from the vehicle and remained trapped beneath the bus due to their injuries. Residents came rushing out of their homes and began helping the the men stuck under the wreckage. Mr Hayward-Powell and one other person scrambled through the exit on the roof of the bus before emergency services arrived on scene.

Seven people were on the bus at the time of the crash, including the driver.

One man, believed to be 18, was airlifted in a stable condition to Royal North Shore Hospital suffering spinal injuries. Four other passengers were taken to John Hunter Hospital suffering minor injuries.

Mr Hayward-Powell was still processing what had happened when he spoke with the Newcastle Herald on Sunday. He returned to the scene of the crash as soon as he was discharged from hospital, suffering from cuts, abrasions and a shoulder injury.

"I can't believe it," he said.

"I've cheated death. It is hard to be here, but I needed to see it for myself."

Emergency crews - police, firefighters and traffic control officers - remained at the scene throughout Sunday morning. The crash investigation unit scoured the site for clues to the cause of the incident, before a crane crew was brought in to remove the vehicle.

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The busy section of road was closed for several hours and onlookers were moved a safe distance away while crews hooked the bus up to the crane and flipped it back onto the road. It was a delicate operation as NSW Fire and Rescue were concerned the bus may have hit a nearby suspended gas line, but luckily the line remained intact. The bus was also leaking fluid, so firefighters monitored the situation until the vehicle could be taken away.

The bus driver, a 61-year-old man, was taken to hospital where he underwent mandatory testing. He was discharged on Sunday morning.

A spokeswoman for bus operator Keolis Downer said the incident was under investigation and that the company would be working with the driver, passengers and their families following the incident.

"While the circumstances surrounding the single-vehicle crash are still under investigation, today's incident has prompted police to remind motorists to take care when travelling on NSW roads, take your time and be aware of other road users and the conditions," Lake Macquarie Chief Inspector Peter Vromans said.

"Traffic and Highway Patrol officers, together with local police, will continue to have a high-visibility presence in metro and regional areas across the state, targeting speeding, fatigue, and drink, drug, dangerous and distracted driving. Police won't hold back in stopping and charging those who choose to break the road rules and put others at risk."

Police enquiries continue.