Police in Foyle have arrested a 19 year-old man in connection with their inquiries into an overnight arson attack in Derry.
Two houses were seriously damaged and another sustained smoke damage in the attack which happened in Fergleen Park, Galliagh.
The houses were evacuated safely and a 19 year-old male was arrested.
He is currently assisting police with their inquiries. Firefighters said one large family - whose home has been completely gutted in the arson attack - were lucky to have escaped with their lives.
"At that time of night the family could have been in their beds upstairs and with the oil tank on fire downstairs they mightn't have been able to get out," insisted Crescent Link Fire Station Commander Martin Jeffrey.
"They are very lucky."
The fire service were called to the scene of the blaze in the huge housing estate shortly after 1am this morning.
A family in one of the houses had already managed to get out while their home and the community house next door, which was empty at the time, burned to the ground.
Another family home in the terrace was badly damaged after the water tank in the roofspace melted with the heat and flooded the house.
Some 20 firefighters, from Derry and Strabane stations, fought the flames for hours before the situation was brought under control.
Commander Jeffrey said fire cover for the city was severely effected at the time with four units needed to tackle the blaze.
Police in Foyle are seeking information from the public and have said they are keen to speak to anyone who may have witnessed the incident.