An elderly man has been seriously injured after being crushed by more than a tonne of plaster in Port Melbourne today.

Paramedics were called to a unit development in Bay Street just before 1.30pm.

WorkSafe spokesman Michael Birt said the delivery driver, aged in his 70s, suffered crushing injuries when a load of plasterboard came off his truck while it was being unloaded in nearby Nott Street.

He said the man was hit by two packs of plasterboard, with each sheet measuring about 3x1 metres.

"He was standing next to the truck while it was being been unloaded and it came off and hit him," Mr Birt said.

Intensive care paramedic Andrew Burns said the man was in severe pain after several sheets of plaster fell on him.

"We were told that he was standing near the sheets of plaster when for some reason they fell and knocked him and pinned him to the ground," he said.

"The plaster was estimated to weigh more than one tonne but thankfully he was quickly freed."

Mr Burns said the man suffered injuries to his chest, abdomen and pelvis. He was taken to The Alfred hospital in a serious but stable condition.

Mr Birt said the accident followed the death of a 37-year-old Bayswater man in Preston on Wednesday morning. The man was unloading a forklift and scissor lift from the back of a truck, when the scissor lift rolled off the truck and crushed him against the forklift, killing him.

He said another man also suffered serious injuries while unloading a truck in the Latrobe Valley on April 24.

"We've been saying for years that drivers should not be standing next to trucks when they're being unloaded because loads do fall off. They can shift in transit, all sorts of things can happen," he said.

"There's been a number of deaths in these circumstances. This sort of thing happens all the time."

WorkSafe inspectors are at the scene and investigations into the incident are continuing.