Authorities say it’s lucky no-one was killed in a major gas main explosion at a busy food court in Sydney’s Chinatown district where hundreds of diners were enjoying dinner.

At least 200 people were in the five-storey building in Haymarket when the explosion occurred in the loading dock of the building around 7.40pm on Tuesday.

Seven people, including a two-year-old boy, were taken to hospital, while nine others were treated at the scene.

#BREAKING At least 14 injured, including two children, in gas explosion in Sydney’s Chinatown pic.twitter.com/spEW5Y9nk0

— CGTN (@CGTNOfficial) November 29, 2016

“We were extremely grateful no one was killed,” NSW fire brigade inspector, Norm Buckley, said from the cordoned-off scene on Wednesday morning.

He said it was a “massive explosion” and there were hundreds of people out and about enjoying the warm night.

“It was quite chaotic”, he told Network Seven.

He said firefighters didn’t have to extinguish a fire as the explosion had consumed the oxygen in the fire, but the damage from the blast has damaged the loading dock.

Many of the injured, including a two-year-old boy, were hurt from flying debris and had to be treated for cuts and bruises.

Paramedics assessed 16 people at the scene with seven taken to Sydney hospitals. The young boy is at Sydney Children’s Hosptial, an NSW Ambulance spokesman said.

Investigators remain at the scene focusing on the basement of the complex where the leak came from.

The building was evacuated on Tuesday night but residents would be able to return on Wednesday.

Karen He, 28, who was in a building next to Dixon House told The Daily Telegraph the gas explosion sounded like thunder.

“My friend and I thought it was a storm or something and did not think too much of it at the time,” Ms He said.

“Then we saw the smoke coming out from the building and then we were worried. But it just sounded like thunder.”

Another witness said a lot of people were in shock.

“It took a couple of seconds to sink in, at the moment, I was just in shock for a while,” he told Nine News.

“It was just unreal. Everyone was looking around wondering what would happen.”