Five other people were injured in the head-on collision, two of whom were airlifted to hospital.
Officials are still investigating what caused the crash, but Malahat fire Chief Robert Patterson says the severity of the collision could have been prevented.
"If there had have been barricades in there, there's a good chance that these people may not have perished."
The provincial government says about 40 per cent of the highway will have a concrete median by spring 2013. The improvements are expected to include cement traffic dividers one kilometre south of the Shawnigan Lake exit, and turning lanes at the intersection.
But Victoria resident Curtis Lindsay says it's too little too late.
"I think the government just really needs to step forward and really come up with good solutions and protect the people driving on the highway," Lindsay said.
"It's a necessity for us to get up and down the island and really it's our only route up and down the island and our route to other communities."
He says every fatal crash on the Malahat has impact on surrounding communities.
"Being a small community here, people will know these people that lost their lives today, and it will affect the community greatly as well."
There has been an average of 58 accidents per year on the highway, including 15 fatalities over the past decade, and police, drivers and residents have long campaigned for more dividers.