The XPT diesel locomotive which derailed killing two people may have been traveling up to 75km/h over the designated speed limit.

Reports have emerged the Sydney to Melbourne train carrying 160 passengers was supposed to have slowed to 15km/h after it was diverted through a different part of the track – a passing loop – at Wallan before it derailed on Wednesday night, killing two people.

Passenger Leyon Gray told the ABC he estimated the train was “probably doing 80 or 90km/h” before everyone was thrown out of their seats.

Some passengers also claimed there was an onboard announcement saying the driver was trying to make up for a lost time, as the train was running at least one hour behind schedule before the crash at 7.45pm.

Police would not confirm this as investigators continued to sift through the wreckage on Saturday.

Canberra man John Kennedy, 54, has been named as the driver who died alongside the train’s pilot, a 49-year-old man from Castlemaine in regional Victoria.

Eleven of the train’s 160 passengers were also injured.

The Australian Transport Safety Bureau is looking at the maintenance of the train and railway line as well as signalling data.

• Related: Train derailment kills two as unions cite dangerous track

Some passengers from the XPT have said it was speeding when it derailed.

A Sydney man described “hanging on for grim death” as the train came off the tracks.

“It probably went about 150 metres before it stopped, there were carriages going sideways – pretty horrifying,” he said.

Passengers and their luggage were thrown about the carriages as the train slid off the tracks onto its side. Photo: Twitter

The Rail, Tram and Bus Union said the the train came off a section of track awaiting maintenance.

“Conditions were altered and V/Line drivers rightly refused to traverse this section over the past week,” secretary Luba Grigorovitch said.

The Victorian Nationals’ deputy leader Steph Ryan raised concerns about the rail line with the state government days before the crash and after another train was derailed further up the line in January.

But Deputy Prime Minister Michael McCormack was not aware of complaints by drivers about the safety of the section of the track.

“No authority would let passengers travel on unsafe track,” he told reporters at the scene.

“We will ensure that proper answers are found for the bereaved families and making sure these sorts of things don’t happen again.”

It’s expected to take days to clear the tracks, with buses set to replace all Seymour, Shepparton and Albury train services until further notice.

The transport safety bureau will release a preliminary report into the crash in about a month, ahead of a final report in 18 months.

-with AAP