Paramedics say they arrived at a "chaotic" and "highly emotional" scene after a ute ploughed into pedestrians a bus shelter on one of Sydney's busiest roads.

Key points: A ute mounted the kerb on Broadway near Victoria Park on Tuesday afternoon, hitting a bus stop

A ute mounted the kerb on Broadway near Victoria Park on Tuesday afternoon, hitting a bus stop Three male pedestrians and the ute driver have been taken to hospital, one man has a critical head injury

Three male pedestrians and the ute driver have been taken to hospital, one man has a critical head injury Heavy traffic continues and motorists have been warned to expect significant delays

One person is in a critical condition and three others in a semi-critical condition after a ute mounted the kerb at Victoria Park in Sydney's Broadway on Tuesday afternoon.

The critically injured man, believed to be in his 70s, was transported to Royal Prince Alfred (RPA) after he sustained a head injury.

The other three bystanders, all males in their 30s or 40s, sustained leg injuries and were transported to St Vincent's Hospital, Royal North Shore Hospital and RPA.

NSW Ambulance Superintendent Kathryn Rallings said the situation paramedics "were confronted with was quite chaotic".

"They're not quite sure what they're going to find, a vehicle into a bus stop can lead into a great number of patients," she said.

"It was a very disturbing scene."

Superintendent Rallings said 10 ambulance vehicles responded to the call around 1:30pm, including intensive care paramedics and a chaplain.

Police and firefighters were also on site.

The driver, a man in his 40s, was also taken to hospital after he was cut out of his vehicle.

The nature of his injuries remains unknown and police said they do not believe the collision was deliberate.

Traffic remains slow on Paramatta Road after the incident, with one of the three westbound lanes closed as the clean-up continues.

Motorists have been warned to expect significant delays.

Buses are experiencing delays of up to 25 minutes through Broadway, Newtown, Erskineville and Alexandria due to heavy traffic.

Police have launched an investigation.