At that time, the angels under Divine command said to Sayyidna Lut (علیہ السلام) : فَأَسْرِ بِأَهْلِكَ بِقِطْعٍ مِّنَ اللَّيْلِ (So, move with your family in a part of night). And asked him to instruct everyone in his family not to turn and look back with the exception of his wife because she was going to be hit by the same punishment that was to fall on his people.
This could also mean that he was not to take his wife along with him. And it could also mean that, being his wife, she was to go along as part of his family, but she would not obey the instruction of not looking back he would give to his family. According to some reports, this is what happened. This wife started off with others, but when she heard the big bang of the punishment given to her people, she looked back and felt sorry at their destruction. At that moment there came a splintered rock and finished her off like others. (Qurtubi, Mazhari)
The angels had also told Sayyidna Lut (علیہ السلام) that: إِنَّ مَوْعِدَهُمُ الصُّبْحُ (The deadline [ of the punishment ] is the morning). He said that he wished the punishment would come sooner. Thereupon, the angels said: أَلَيْسَ الصُّبْحُ بِقَرِيبٍ (Is it not that the morning is near?)
After that, the Qur'an portrays the occurrence of the punishment by saying: So, when Our command came, We turned whatever there was in their habitat upside down raining such stones over it as had the names of everyone there marked on it.
Reports say that these habitations were composed of four major towns where those people lived. These very habitations have been named as 'al-mu'tafikat' (the towns overturned) elsewhere in the Holy Qur'an (9:70, 69:9). When the Divine command came, the archangel Jibra'il al-Amin dissected the base of the land mass holding all those towns on top of it with his wing, raised all of it upwards in a way that everything stayed where it was, even water in a water vessel. It was in the backdrop of human, animal and canine voices coming from the sky that he heaved all these habitations straight up towards the sky and, then, threw the whole thing back upside down - as appropriate to and as called for by the evil they indulged in.