A man and a woman are dead and a driver in hospital after a truck veered off a “dead straight road” and slammed into a house.

Jim Madden, 81, and wife Carmel, 80, were at home in Tower Hill in Victoria’s south-west when the truck veered off the Princes Highway and crashed into their property just after 7am on Friday.

Footage from the scene shows the truck crashed through a paddock, into a fence about 200 metres away and down one side of the house before collecting part of the roof.

The truck driver, a 70-year-old Portland man, suffered non-life threatening injuries and was taken to hospital for treatment.

Detective Sergeant Stephen Hill said the cause of the crash was under investigation.

“We’re keeping an open mind as to what was going on,” he said at the scene on Friday.

“Whether it’s a mechanical fault with the truck, whether there’s a medical episode involved, whether it’s inattention, whether it’s phone use involved, all those things will have to be looked at in the next few days.

“Clearly there’s a real question, given the length of the rolling tyre prints through the paddock, as to how the driver wasn’t able to stop the truck prior to colliding with the house.”

Hill said it appeared the truck was travelling at the correct speed limit of 100km/h at the time of the crash. He described the section of the road as “dead straight” and said there would be no reason for vehicles to swerve unless they were overtaking.

Local business owner Richard Crawley said the Maddens were farmers with many family connections to the area and he expected the crash to affect the community.

“It will have a big impact, Jim and Carmel Madden were very well-known people,” Crawley said.

About 100 people live in the Tower Hill area, according to the 2021 census.

Crawley said he drove near the house in the hours after the crash, before he was diverted away.

“It’s sort of hard to fathom what actually has happened, because it doesn’t make any sense at all that a bloody great big B-double truck on a dead straight part of the highway can do what it did,” he said.

Images from the scene showed one corner of Madden’s home was extensively damaged, with its tiled roof collapsing and debris strewn across the front yard.

The front of the truck sustained little damage except for broken front windows and a broken mirror.

The couple’s bodies remained on the scene on Friday afternoon.

Detectives from Victoria Police’s major collision unit have travelled about three hours from Melbourne to the scene to investigate.

Anyone with information about what happened or relevant footage is urged to contact police.

-with AAP