The Angels were sent to destroy the People of the Prophet Lut
Allah the Exalted said about Ibrahim, peace be upon him,
فَلَمَّا ذَهَبَ عَنْ إِبْرَاهِيمَ الرَّوْعُ وَجَاءتْهُ الْبُشْرَى يُجَادِلُنَا فِي قَوْمِ لُوطٍ
إِنَّ إِبْرَاهِيمَ لَحَلِيمٌ أَوَّاهٌ مُّنِيبٌ
يَا إِبْرَاهِيمُ أَعْرِضْ عَنْ هَذَا إِنَّهُ قَدْ جَاء أَمْرُ رَبِّكَ
وَإِنَّهُمْ اتِيهِمْ عَذَابٌ غَيْرُ مَرْدُودٍ
Then when the fear had gone away from (Ibrahim), and the glad tidings had reached him, he began to plead with Us for the people of Lut. Verily, Ibrahim was, without doubt forbearing, used to invoke Allah with humility, and was repentant. "O Ibrahim! Forsake this. Indeed, the commandment of your Lord has gone forth. Verily, there will come a torment for them which cannot be turned back." (11;74-76)
Allah said here,
قَالَ فَمَا خَطْبُكُمْ أَيُّهَا الْمُرْسَلُونَ
(Ibrahim) said;"Then for what purpose you have come, O messengers!"
meaning, `what is the mission that you were sent with,'
قَالُوا إِنَّا أُرْسِلْنَا إِلَى قَوْمٍ مُّجْرِمِينَ