His saying: "Has there reached you" means: it has indeed reached you. "The report of the Overwhelming [Event] (Al-Ghashiyah)" refers to the Resurrection—according to the interpretation of Al-Hasan—which envelopes mankind with its torment and punishment.
قَوْله: ﴿هَل أَتَاك﴾ قد أَتَاك ﴿حَدِيث الغاشية﴾ يَعْنِي: الْقِيَامَةَ - فِي تَفْسِيرِ الْحَسَنِ - تَغْشَى النَّاسَ بِعَذَابِهَا وَعِقَابِهَا