Emergency services were called around 8:10am after reports a car had "flipped and went down and embankment" heading northbound, according to Sutherland police.

"Two vehicles were merging, one has flipped onto it's roof in the breakdown lane," Inspector Matt Webb said.

"[It] then flipped over the guard rail and landed over the embankment the right way up."

A NSW Ambulance media spokeswoman said two patients were taken to St George Hospital by road with minor injuries.

A rescue helicopter had been tasked but was called off, as no longer needed.

Some traffic delays heading northbound were still being experienced at 9:40am.

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Earlier: Traffic delays are being experienced heading northbound on the M1 Princes Motorway near Waterfall on Monday morning after a car crash.

One of two northbound lanes were closed at 8:35am, with emergency services on scene - about six kilometres south of the intersection of Kooraban Street.

A NSW Police spokeswoman said it has been reported a car may have hit a guard rail after a two vehicle accident just before 8:30am.

It's uncertain if anyone has sustained any injuries. NSW Ambulance are also on scene.

Motorists are advised to reduce speed and exercise caution.

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