At 12.30am on Sunday 13 February, the three victims were travelling from Amersham to Harrow-on-the-Hill when they heard a man arguing with the woman he was with.
The three victims looked at the pair, and the man responded aggressively before punching and kicking one of the victims.
The woman then got involved and the pair unleashed a sustained attack on all three victims.
As a result of the attack one of the victims suffered a broken ankle and another suffered bruising to the brain.
Officers believe the two people in the images may have information which could help their investigation.
If you recognise either of them, or witnessed the incident, please contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 33 of 13/02/22.
Alternatively, you can call Crimestoppers anonymously on 0800 555 111.
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