6. In the complex plane, the points corresponding to the complex numbers $z_{1}, z_{2}, z_{3}$ are $Z_{1}, Z_{2}, Z_{3}$, respectively. If $\left|z_{1}\right|=\left|z_{2}\right|=\sqrt{2}, \overrightarrow{O Z_{1}} \cdot \overrightarrow{O Z_{2}}=0$, $\left|z_{1}+z_{2}-z_{3}\right|=2$, then the range of $\left|z_{3}\right|$ is $\qquad$.
Suppose $Z_{1}(\sqrt{2}, 0), Z_{2}(0, \sqrt{2})$, then the trajectory of $Z_{3}$ is a circle with the point corresponding to $z_{1}+z_{2}$ as its center and 2 as its radius. Combining the graph, we know $\left|z_{3}\right| \in[0,4]$.