A huge fire that took hold of a large central Watford office block yesterday started in an electrical riser, preliminary investigation has found.

Fire investigators have been examining the damaged building at 64 Clarendon Road, opposite Watford Junction Station, this morning after flames spread through the fourth floor and roof.

Jon Horastead, station commander for Watford and Three Rivers, told the Watford Observer criminal activity had already been ruled out as a cause.

Watford Observer:

Smoke billowing from the front of the offices yesterday afternoon.

He said: “It appears to be have been an electrical fire. We have ruled out any criminal activity.

“It seems to have started in an electrical riser but what the cause is we don’t know. I think what will happen is we will have to take the electrical equipment away to test if further.”

The fire began on the fourth floor at around 7.20pm yesterday before a huge pall of smoke was billowing from the building.

Fire crews fought the blaze inside the building and outside from an aerial platform until around midnight.

Watford Observer:

Firefighters spraying the roof from an aerial platform. Picture by Warren Reid

Mr Horastead added the top floor was badly damaged but that office workers were looking to return to the lower levels in the next few days.

He said: “The fourth floor is most badly affected with about 40 per cent smoke and fire damage.”