A Police Scotland helicopter was used to hunt for suspects, after a van was deliberately set alight.
Officers carried out a search by air and land after a Ford Transit van was discovered on fire near Newtongrange in Midlothian.
The incident happened around 10.30pm on Saturday night.
Residents reported seeing the police helicopter overhead.
Officers say they are treating the incident as deliberate and enquiries are ongoing.
A police spokesman said: "Police Scotland was made aware of a Ford Transit van which was found on fire off the B704 near Newtongrange around 10.30pm on Saturday, 17 May.
"The fire was extinguished by the Scottish Fire and Rescue Service.
"Nobody was found within the van and a search was carried out of the surrounding area by officers, with support from the Police Scotland helicopter.
"The fire is believed to have been started deliberately and enquiries are ongoing to establish the full circumstances."
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