Safety-critical control systems increasingly rely on networking technologies, which makes these systems vulnerable to cyber attacks that can potentially jeopardise system safety. To achieve safe- and secure-by-construction development, the designers should analyse the impact of security attacks already at the modelling stage. Since SysML is often used for modelling safety-critical systems, in this paper, we propose to integrate modelling in SysML and Event-B to enable reasoning about safety-security interactions at system modelling stage. Our approach combines the benefits of graphical modelling in SysML with the mathematical rigor of Event-B to visualise and formalise the analysis of the impact of security attacks on system safety.