Fire in nuclear plant, Antwerp, Belgium

[link to www.nu.nl]

Rough translation:
"In the nuclear plant in Doel, north of Antwerp, a fire broke out tuesday afternoon. Despite the amounts of smoke a spokesperson of the firedepartment of Beveren states there is no risk for the neighborhood.

The fire department hasn't found out yet were the fire comes from. The emergency plan of the nuclear plant is in effect.

There is no further information yet. There are no casualties."

How can one say there is no risk if the cause of the fire has not been found?