A 17-year-old girl was questioned by police after at least two homeless men sleeping rough were set on fire.
Met Police are investigating a number of worrying incidents this week which have seen one or more people set fire to rough sleepers.
Detectives in Croydon, south London, believe others may have been targeted and are appealing for any further victims and any witnesses to come forward.
Two men were treated by the London Ambulance Service for minor burns after they were set on fire on Monday morning.
Police say their sleeping bags or other property were also set alight.
A Met Police spokesperson said: “At around 05:00hrs on Wednesday, 12 June, a man and a female were stopped by police on George Street in Croydon and arrested.
“The 22-year-old man was later charged and is due to appear in court on Thursday, 13 June.
“The 17-year-old girl was bailed until a date in July pending further enquiries.”