Sforno on Exodus 11:6/ספורנו על שמות י״א:ו׳

1אשר כמוהו לא נהיתה, never had there been such an outcry in any of the nights the Egyptians had known. The reason was that this was not a night during which a battle was being waged against the enemies of the Egyptians, an occasion when there are many outcries in the city, as we know from Tzefaniah 1,10 “a loud outcry from the fish gate and howling from the Mishneh, and a great sound of anguish from the hills. The dwellers of the Machtesh howl.” This was a night during which Egypt was at peace. Never again would there be such an outcry in the midst of peace.