Two children have allegedly been assaulted at the St Peter Port bus terminus.
Police say it happened at around 5:25pm on Tuesday 31 May.
Officers want to speak to anyone who saw what happened.
The force also wants people in the South Esplanade and bus terminus area with CCTV to come forward.
Anyone with information is asked to call PC55 Le Bachelet on 222 222 or Crimestoppers anonymously on 0800 555 111.

Prime Guernsey seafront location for sale
Woman (20) arrested on suspicion of attempted murder in Guernsey
Last day to register for Guernsey's upcoming by election
New citizen science project observing Guernsey dragonflies and damselflies
Channel Islands music school to hit global stage with Dubai launch
67,000 sickness days across the States of Guernsey last year
The Channel Islands are officially in meteorological drought
Islanders asked for views on body image and masculinity