A car and a van have been damaged by fire at Merriman Court in Ballymagroarty.
At around 1am today, a youth was seen pouring flammable liquid over three vehicles. There was minor damage to two of them.
At this stage a motive has not been established.
The youth was wearing a white hooded top and police at Strand Road are keen to hear from anyone who can help identify him. Information can be given on the police non-emergency number 101. Alternatively, it can be provided to the Crimestoppers charity anonymously on 0800 555 111.