Police say the boys, aged around 16, leapt into the van when the driver was making deliveries in Preston Road (A6) at around 12.20pm.
The van was found abandoned in nearby Maypark, where the pair were spotted fleeing with armfuls of looted parcels down a ginnel towards Cuerden Valley Park.
Amazon packages addressed to homes in the area were discovered ripped open and strewn around the grounds of the park.
The boys are also suspected of attempted burglaries in the area on Monday, where they were allegedly seen entering garages in Daisy Meadow and Well Orchard.
Police are also investigating an incident that day where two boys matching their description brandished a knife and threatened two young girls playing at the park in Green Leaves. You can read more about the incident here.
No arrests have been made at this stage, but Lancashire Police are asking for witnesses or anyone with CCTV or doorbell footage to get in touch.
A police spokesman said: “ On Monday, May 2, an Amazon van was stolen from Preston Road in Clayton Brook and was found abandoned two minutes later on Maypark.
“The two offenders are described as white males wearing all black and aged approximately 16 years old.
"They were seen running from the van towards the ginnel into Cuerden Valley at 12.22pm, where they were opening the stolen parcels.”