The bodies of more than 70 refugees have now been found in the back of an abandoned lorry on an Austrian motorway.
Forensic investigators have worked through the night to remove the decomposing bodies and establish how many migrants had died.
Local media reports have suggested that the migrants died of “suffocation” after being trapped in the lorry’s trailer.
The corpses were found in the back of the refrigerated food delivery truck, which had been parked on the hard shoulder of the A4 road, Austria's “Eastern Motorway”, near the town of Parndorf.
An Austrian police motorway patrol officer had seen fluids seeping from its back door.
The truck is towed along a highway near Neusiedl am See, Austria
A police manhunt has been launched to find the driver of the lorry, who is suspected of smuggling the victims into the country.
Police said the people may have already been dead when the lorry entered the country from Hungary the previous night.
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The bodies will now reportedly be to taken to Vienna for post-mortem examinations.
Austria's interior minister Johanna Mikl-Leitner criticised the "despicable methods" of migrant smugglers at a press conference yesterday, saying they "belong behind bars".
