A woman was left with head and facial injuries following an early morning attack in Liverpool city centre.
Emergency services were called to Vernon Street shortly before 4am following reports that the 38-year-old had been assaulted.
The woman was taken to hospital where police say her injuries are not thought to be life threatening.
Detectives have cordoned off the area while enquiries are on-going as they prepare to speak to witnesses and examine CCTV from the area.
Merseyside Police have urged anyone who has any information about this incident to contact Liverpool CID on 0151 777 4886/4825 or Crimestoppers anonymously on 0800 555 111.