The thunderclap seized the children of Israel and they died. Then Allah U brought them back to life after their death.
As for Musa u, he did not die. Rather, he fell unconscious due to the great glory of Allah U manifested onto the mountain. When he regained consciousness:
﴾فَلَمَّا أَفَاقَ قَالَ سُبْحَانَكَ تُبْتُ إِلَيْكَ وَأَنَا أَوَّلُ الْمُؤْمِنِينَ﴿
“And when he awoke, he said, “Exalted are You! I have repented to You, and I am the first of the believers.’” [Surah Al-A’raaf: 143]
He u repented from ever asking this again.