A 28-year-old woman was assaulted and a tent set on fire on land underneath the railway in Old Potts Way.
It happened around 9.10pm on Sunday and detectives are urging any witnesses to come forward.
The woman suffered minor injuries as a result of the assault.
A 38-year-old man has been arrested on suspicion of arson with intent to endanger life and with assault.
Police say inquiries are ongoing.
Any witnesses are asked to contact West Mercia Police via the Tell Us About section at westmercia.police.uk
Alternatively, contact Crimestoppers anonymously on 0800 555111 or at crimestoppers-uk.org