The Story of the Dwellers of the Town and Their Messengers, a Lesson that Those Who belied Their Messengers were Destroyed

Allah says, `O Muhammad, tell your people who disbelieve in you,'

مَّثَلاً أَصْحَـبَ القَرْيَةِ إِذْ جَآءَهَا الْمُرْسَلُونَ

In the next sentence of verse 13: إِذْ أَرْ‌سَلْنَا إِلَيْهِمُ اثْنَيْنِ فَكَذَّبُوهُمَا فَعَزَّزْنَا بِثَالِثٍ فَقَالُوا إِنَّا إِلَيْكُم مُّرْ‌سَلُونَ (when the messengers came to it... - 13). The text has briefly mentioned the coming of messengers to the town. The number of the messengers sent has been identified in verse 14:إِذْ جَاءَهَا إِنَّا إِلَيْكُم مُّرْ‌سَلُونَ (when We sent to them two (apostles), and they rejected them both, so We supported them with a third one. So they said, "We are sent to you" ) This shows that three messengers were sent to the said town. First came two, the people of the town rejected them and refused to listen to them. Then Allah Ta’ ala strengthened them by sending the third messenger. After that, all three addressed the people of the town, telling them that they had been sent to guide them to the straight path.

What does 'messenger' mean? Who were these people?