Six men have been bailed over an incident in which a woman was allegedly assaulted at a house in Sunderland.
The 26-year-old woman suffered cuts and bruises in the incident at a house in Peel Street, Hendon, overnight between Saturday and Sunday.
Southern Area Command Chief Inspector Paul Milner said: "We know the woman had been in Sunderland City Centre on Saturday night before waking up in a strange address in Peel Street with cuts and bruises.
"She managed to leave the house and get to a family member's home at around 5am on Sunday morning.
"The victim believes her drink may have been spiked.
"This is obviously a very serious incident and something we know the local community will be concerned about and we will have officers on patrol to offer reassurance to anyone who may be concerned and answer any queries they may have.
"If anyone has any information they think may be useful to our investigation then I would ask them to get in contact with us."
Six men have been released on bail until October 17.
Anyone with information should contact Northumbria Police on 101 quoting reference 572 040916 or Crimestoppers anonymously on 0800 555 111.