Newly released CCTV shows a man police would like to speak to in connection to the incident, which took place at around 1.30am on Sunday, November 21, 2021 on Castle Lane, Bedford.
Nine people have been arrested in connection with the incident. However, police would still like to trace two people who may have further information.
The independent charity Crimestoppers is now offering a £1,000 reward for information which can help identify them.
People can submit information anonymously through Crimestoppers and would not have to go to court.
Detective Superintendent Will Hodgkinson, Bedfordshire Police's lead for robbery, said: “We are hoping that anyone viewing this might recognise the man in the white t-shirt, or have further information which can help our investigation.
“We are really grateful to Crimestoppers for coming forward and offering this reward.
“If you can help us, please get in touch.”
Anyone with any information is asked to contact Bedfordshire Police via beds.police.uk/ro/report and quote Operation Fakenham.
You can also give information anonymously via Crimestoppers on 0800 555 111 or by visiting crimestoppers-uk.org.