Oakland police say they found a man inside the van, who was shot dead.
"At this point, the belief is that the incident did occur on the freeway," said CHP Officer Andrew Barclay.
Officer Barclay says it is still early in the investigation. Police are still trying to determine a motive.
"Based off information that we received, a portion of 580 near the seminary off-ramp in Oakland was closed for a period of time to allow our detectives to conduct an investigation at that specific location," he said.
RELATED: Man found dead inside van likely victim of freeway shooting in Oakland, authorities say
It is the fifth fatal shooting in Oakland just this week. Gun violence is a major talking point for candidates heading into the November elections.
Oakland City Council President Pro Tempore and mayoral candidate, Sheng Thao, shares her analysis of what may be behind much of the violence.
"There is a small population, a small population of people, who are committing these heinous murders. And that's what we need to focus on," Thao said.
She says she has personally been working on new strategies with Oakland Police Chief LeRonne Armstrong.
That would include expanding the police department's homicide investigation unit, which currently faces a huge backlog. Furthermore, she thinks it is important to strengthen partnerships with the county and neighboring cities.
RELATED: 4 homicides in Oakland in less than 24 hours; latest happening outside City Hall
"People are coming in from Hayward, Concord, San Francisco to do the shooting, and then fleeing. And so we want to make sure that we have connectivity, that connection with the county and other cities as well," Thao said.
Thao, along with others, says it's time to double down on violence prevention. She says that involves improving the socioeconomic conditions of many neighborhoods.
City Councilmember Loren Taylor, who is also running for mayor, spoke about it at an Oakland mayoral candidate forum on Wednesday.
"We also have to make sure we are bringing the crime deterrents, the enforcements, and the follow up investigations that are necessary to make a complete public safety system," Loren said to the crowd.
But Oakland residents, like Nenna Joiner, say they've heard these slogans before. She's now running for an Oakland city council seat.
RELATED: 2 officers injured, 3 killed in separate shootings after violent 24 hours in Oakland
On July 13, there was a triple shooting in downtown Oakland, which left one man dead. It was just a block away from Joiner's downtown business.
Joiner, who has lived in the city for 27 years, says the fatal shooting in front Oakland City Hall on Tuesday, is still impacting residents.
"That shooting at city hall has caused a lot of corporate employees to say they are not coming back to work. So, there is a direct impact to everybody," Joiner said.
Along with hiring more police, she, too, is calling on violence prevention, but also poverty prevention. She adds that this work can't be left up to the politicians alone.
"The police, we talk about other departments in the city of Oakland. We also have to remind ourselves, as citizens, we also have an invested stake, and making sure that we get out there in our community and make it safe for ourselves as well," Joiner said.