Detectives are investigating after two rough sleepers were set alight.
The men were treated for minor burns after their sleeping bags and other property was set on fire in Croydon, south London, officers say.
Police believe others may have been targeted and are appealing for any further victims and any witnesses to come forward.
They say two cases were reported around George Street and Surrey Street in Croydon in the early hours of Monday.
Two people were arrested in the area on Wednesday.
A 22-year-old man has been charged, and a 17-year-old girl who was with him has been bailed while further enquiries are carried out.
