Two people were left trapped and four have been seriously injured after a collision between a bus and a car in Sydney.

Emergency services responded to a “nose to tail” crash on the M2 at Macquarie Park in the city’s north-west about 3.40pm today.

The bus driver and one passenger were left trapped and paramedics worked to rescue them for “some time”, Fire and Rescue NSW Zone Commander Joshua Turner said.

Bus crash Sydney's M2The bus driver and one passenger in a car are trapped and rescue crews are now on the scene. (9News)

The trapped driver and passenger have since been taken to hospital.

There were around 40 passengers on the bus.

Four passengers were treated at the scene and have been taken to hospital in a serious but stable condition.

FRNSW Joshua TurnerFRNSW’s Joshua Turner. (9News)

Another seven people suffered minor injuries.

Five people in a SUV also suffered minor injuries.

The remainig 27 passengers have been transferred to a replacement bus.

Police described the rescue as having a “very good outcome”.

Motorists in the area were warned of significant traffic impacts.