Pregnant woman and husband escape car fire that shut down major tunnel

A heavily pregnant woman and her husband escaped from a car fire that shut down a major Sydney motorway at noon today.

Sebastian and Gretta Lough were driving through the Eastern Distributor near the Randwick Bondi exit when their Hyundai began smoking, eventually catching fire in the southbound lane of the motorway.

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"There was smoke coming and cars were beeping at us we had our hazards on," Gretta told 9News.

"I was freaking out at first but I knew I had to calm down."

NSW Fire and Rescue mechanic Belinda Jackson was first on the scene and helped the couple to safety.

"I pulled her to safety into the fresh air in the cabin," Jackson said.

"She was quite distressed watching her car on fire, and I just wanted to make sure she was OK."

Jackson was treated for smoke inhalation after helping the couple.

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NSW Ambulance confirmed to 9news.com.au that two people, a man and a woman in their 30s were taken to hospital, but could not say why they were taken into treatment.

The Eastern Distributor was forced to close in both directions, along with the southbound lanes of the Sydney Harbour Tunnel following the incident.

Traffic was backed up along a stretch to four kilometres to St Leonards southbound, while traffic headed north was backed up for 7km to Roseberry.

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The southbound lanes of both tunnels have since re-opened.

Some motorists were left waiting in their cars for an extended period of time, while others were forced to abandon their vehicles, walking out of the tunnel on foot to escape the smoke.

Motorists in the area were being warned that traffic was "very heavy" in both directions, however, it is now flowing steadily.