A Swedish man was killed and another seriously injured when the shopping trolley they were joyriding slammed into a car in Sydney's east.

Key points: The trolley collided with a car travelling on a road within the speed limit

The trolley collided with a car travelling on a road within the speed limit One man was in the trolley, and another behind it

One man was in the trolley, and another behind it They said pair were "mucking around" before the crash

One man, 28, was in the trolley on Coogee Bay Road at Randwick, while another man, also 28, was riding behind it.

The man inside the trolley died at the scene after he was "catapulted out" during the crash just after midnight, while the other man was taken to hospital in a serious but stable condition.

Police said one of the men was a student and the other was visiting Australia from Sweden. Officers did not specify which of the two had died.

Detective Superintendent Gavin Dengate from the Eastern Beaches command said the trolley smashed into a car travelling in the opposite direction near Judge Street.

"We do know the car heading west was travelling [at] what we believe was within the speed limit," he said.

"It's a 60 kilometre per hour zone and at 60kph, that is fast enough to kill you.

"The male that was in the shopping trolley was catapulted out, landing in a kerb on the southern side of the road, the other person landed after the collision in the middle of the road."

Detective Superintendent Dengate said it appeared the men were simply "mucking around" before the crash, and the driver of the car was not at fault.

"We're conducting inquiries into a number of areas but that's certainly one theory, but certainly not the only theory that we're looking at," he said.

"From initial inquiries, it's believed they would have been skylarking, or maybe using it as some form of vehicle.

"But we're still yet to find out exactly what happened.

"I suppose we all know, because we've all used shopping trolleys, how dangerous they are, how you can't manoeuvre a shopping trolley.

"It must be one of the most dangerous things you can do."

The crash happened at the corner of Coogee Bay Road and Judge Street in Randwick. ( Supplied: Ryan McCann )

The 45-year-old driver of the vehicle was taken to hospital for mandatory blood testing, but was not hurt.

Detective Superintendent Dengate said a number of passers-by stopped as well as the driver of the car.

"They stopped and helped people they saw were in need, in a very bad need of some urgent attention," he said.

The police investigation continues.

Local resident Victoria James said it was a shocking accident.

"It wasn't very nice for my children, walking up there this morning ... there's blood up there and it's all very nasty," she said.