Investigators are examining the cause of a blaze that ripped through a derelict building in Hamilton in the early hours of yesterday morning.Emergency services were called to the scene on Cedar Avenue at around 1.15am. The fire raged for several hours and it is understood that at least three fire trucks were needed to bring the blaze under control.The building used to be home to the Teen Services charity, although it is no longer in use and is understood to now be abandoned.But authorities have refused to confirm that the building was unoccupied at the time of the blaze, saying that a full search of the property needed to be carried out.Just after 6am, a police spokesman confirmed that the fire had been extinguished and the road reopened to motorists.“The investigation into the cause of the fire is ongoing,” the spokesman added.One eyewitness living across the street from the building said she was woken by a flatmate at about 1.40am.“There was quite a bit of noise and we could see flames coming from the roof,” she said.The witness claimed that firefighters had to replenish water supplies from the apartment block located outside the building.