A method for safeguarding a hazardous working area of an automated machine comprising the steps of: - providing at least one sensor unit which provides a respective current 3-D image of the working area at defined intervals of time, - defining at least one protection zone in the working area, - cyclically monitoring the protection zone using a fail-safe foreign object detector which generates a first signal on the basis of the respective current 3-D image and the defined protection zone if a foreign object is detected in the protection zone, the first signal comprising a first item of position information which is representative of a position of the foreign object in the protection zone, - cyclically classifying the foreign object in the protection zone using a classifier, characterized in that the classifier generates a second signal if the foreign object is identified as a person, wherein the machine is operated on the basis of the first and at least the second signal (51, 65), and further comprising the steps of - tracking an identified person over a series of the respective current 3-D images using a person tracker, the person tracker determining, after each new 3-D image, a second item of position information which represents a current position of the identified person in the protection zone, and - comparing the first and second items of position information in order to determine whether the first item of position information from the foreign object detector and the second item of position information from the person tracker each represent identical positions, wherein the machine is stopped if the position of the foreign object according to the first item of position information and the position of the identified person according to the second item of position information are different from one another. - providing at least one sensor unit which provides a respective current 3-D image of the working area at defined intervals of time, - defining at least one protection zone in the working area, - cyclically monitoring the protection zone using a fail-safe foreign object detector which generates a first signal on the basis of the respective current 3-D image and the defined protection zone if a foreign object is detected in the protection zone, the first signal comprising a first item of position information which is representative of a position of the foreign object in the protection zone, - cyclically classifying the foreign object in the protection zone using a classifier, characterized in that the classifier generates a second signal if the foreign object is identified as a person, wherein the machine is operated on the basis of the first and at least the second signal (51, 65), and further comprising the steps of - tracking an identified person over a series of the respective current 3-D images using a person tracker, the person tracker determining, after each new 3-D image, a second item of position information which represents a current position of the identified person in the protection zone, and - comparing the first and second items of position information in order to determine whether the first item of position information from the foreign object detector and the second item of position information from the person tracker each represent identical positions, wherein the machine is stopped if the position of the foreign object according to the first item of position information and the position of the identified person according to the second item of position information are different from one another. - tracking an identified person over a series of the respective current 3-D images using a person tracker, the person tracker determining, after each new 3-D image, a second item of position information which represents a current position of the identified person in the protection zone, and - comparing the first and second items of position information in order to determine whether the first item of position information from the foreign object detector and the second item of position information from the person tracker each represent identical positions, wherein the machine is stopped if the position of the foreign object according to the first item of position information and the position of the identified person according to the second item of position information are different from one another.