'Good man' and rideshare driver killed in triple fatal Sydney crash

A driver involved in a horrific triple-fatal crash in Sydney's south overnight was visited by police just moments earlier.

Police were first called to Gymea Bay for a welfare check about 12.25am.

Upon arrival, NSW Police Detective Acting Superintendent Graham Hibbs said that they found a man in the driver's seat of a white Audi sedan.

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Police said Tamati Gilbert was the 42-year-old driver of the vehicle.

"Before police had the opportunity to speak with that male person, he left the scene," he said.

About 10 minutes later, emergency crews were called to a "horrific scene" on Captain Cook Bridge at Sans Souci after receiving reports of a two-vehicle crash, with one car on its roof.

When police arrived at Rocky Point Road, they found that the white Audi sedan had collided head-on with a blue Camry sedan after travelling at what police believe was "considerable speed".

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"Tragically, the occupant of the white Audi was found to be deceased by police, as were the two occupants of the blue Camry," Hibbs said.

Seamus Duignan and a 20-year-old rideshare driver were inside the vehicle.

Duignan was on his way home from a concert to celebrate his 28th birthday with friends.

Today his brother paid tribute, describing him as "a good man, brother and uncle" who was "never in trouble, just a good man who loved a laugh".

Hibbs said that there were up to 40 people, including witnesses and onlookers, trying to help the men when police arrived.

"Grabbed the fire extinguisher, gave it to somebody and just checked that people weren't trapped inside," one helper told 9News.

"My main concern was trying to get people out and the car not blowing up and that's it."

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Hibbs described the crash scene as "horrific".

"I can tell you that and if you've seen any images from down there, it wouldn't be nice for any person to see that scene," Hibbs said.

The site was sealed off this morning with traffic diversions in place to allow crash investigators to piece together crucial evidence. 

Locals told 9News the crash site has always been a dangerous stretch of road.

They are calling for speed cameras at either end of the bridge to prevent future incidents.

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