A truck, a bus and cars have been damaged in a crash in Ryde

A bus has been severely damaged by a truck after a shocking smash in northwestern Sydney. Several vehicles have been involved in the crash.

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A truck and a bus have collided on Church St in Ryde.

Several vehicles have been involved in the crash on Church St at the Junction St intersection. For a time Church St was closed both southbound, and northbound; towards the city.

The M41 bus heading towards Top Ryde at 10am when the collision occurred with a black Audi 4WD.

The female driver was trapped for 30 mintues but has now been flown to Royal North Shore Hospital with head and internal injuries.

Lanes remain closed and Traffic NSW is warning motorist to prepare for detours.

A truck has collided with a bus on Church St in Ryde closing down lanes and backing up traffic. Picture: Traffic and Highway Patrol Command - NSW Police Force

Two southbound lanes of Church St are now open at the site of the crash.

One southbound lane of Church St remains closed near Junction St.

Traffic is still very heavy in the area and motorists are still advised to allow plenty of extra travel time. Some buses in the area are delayed by up to 50 minutes.

Emergency services and traffic crews remain at the crash site.

The crash brought down the lights at on Church St, halting traffic. Picture: Traffic and Highway Patrol Command - NSW Police Force

The damage to the bus was extensive. Picture: Traffic and Highway Patrol Command - NSW Police Force

Route 458 buses are only operating between Burwood and Rhodes and are delayed up to 40 minutes.

Traffic on Church St has been brought to a standstill. Picture: @JohnKGBaldock

Route M41 buses are diverting and are delayed by up to an hour.

A woman was among drivers injured in the crash.

Emergency crews were called to the intersections just after 10am following reports an Audi and the truck had collided before careening into the other vehicles.

As well as the driver, three other people were also injured in the smash and have been taken to Concord Hospital.

A NSW Police spokesman said the truck lost control after colliding with the Audi, setting off the chain reaction crash.

“Police were told a truck and an Audi crashed, with the truck then crashing into a bus and several other vehicles,” he said.

“We’ve also been told the bus crashed into another bus.”

Investigators have launched a probe into what caused the Audi and truck to clip each other.

Traffic is banking up and motorists are advised to avoid the area.

Pictures of the scene show the gruesome wreckage of the truck wedged into the side of a bus.

The crash scene extends for more than 100 metres, police said.