A couple may have been attacked in a skate park because they were goths, police in Lancashire have said.
The 21-year-old man and his girlfriend, aged 20, were found with serious head injuries in the park at Stubby Lee.
Their faces were so badly swollen that police could not tell which person was male and which was female.
Five teenage boys, aged between 15 and 17, have been charged with section 18 wounding but officers are still appealing for witnesses.
The couple were initially taken to Fairfield General Hospital but later transferred to a hospital in Manchester.
They remain in a serious but stable condition, a police spokeswoman said.
Det Insp Dean Holden, leading the inquiry, said: "We believe they were attacked by a large group of people and we are still looking for other offenders."
All five youths are due to appear at Burnley Magistrates' Court on Monday.