Melbourne's Burnley tunnel remains closed following a multi-vehicle pile-up that killed three people on Friday.
A fire in the tunnel sparked by the accident forced the evacuation of 400 people from their vehicles.
Victoria Police said the death toll from the tunnel blaze remains at three and the deceased are yet to be identified.
Jean Ker Walsh, spokeswoman for Transurban, the tunnel's operator, said it was not yet known when the 3.4km tunnel would be reopened to traffic.
"We're waiting now for an internal briefing from our engineers," Ms Ker Walsh told reporters. "There's no scheduled time for reopening."
Ms Ker Walsh said the extent of possible structural damage to the tunnel as a result of the accident was not known.
Police investigating the incident are seeking surveillance camera footage.
The collision between four trucks and three cars deep inside the tunnel forced the evacuation of hundreds of motorists in both the Burnley and Domain tunnels.
Motorists later spoke of "huge" flames erupting from the crash scene.
The 3.4km long Burnley tunnel - which passes under the Yarra River to bypass the CBD - joins West Gate Freeway with the Monash Freeway.
Assistant Commissioner Ashby said a vehicle broke down in the left hand lane of the tunnel, about 1.5km from the south-east exit, just before 10am.
"Another vehicle has collided with the rear of that vehicle and as a consequence there's then been a series of other crashes, so secondly, and we believe also a third collision that's occurred.
"As a consequence we have three semi-trailers vehicles that have been involved, we've got four other vehicles, we've also had three people who are confirmed to have lost their lives and they've lost their lives in three separate vehicles."
The inbound Domain Tunnel was also closed during the incident. The closure of the tunnels plunged city traffic into chaos.
Premier Steve Bracks has expressed his condolences to the families and friends of those who died.