||After a lot of recent natural and human-made disasters all over the word, the large scale emergency response process is becoming very critical and challenging. Lives can be lost and property can be harmed. To respond to these major threats, an effective operational emergency response system needs to address the necessity of data sharing, information exchange and correlation between different Emergency Responders (ERs) including firefighters, police, health care services, army, municipality and so on to successfully respond to large scale disasters. Therefore, the goal of this paper is to introduce POLARISC, an interoperable software solution based on a common and modular ontology shared by all the ERs. Its main objective is to solve the problem of semantic difference and heterogeneity of data to guarantee a common understanding among the various ERs in order to coordinate and to obtain a real time operational picture of the situation.