Exodus 12:28-30

28Then the children of Israel went away and did so; just as the Lord had commanded Moses and Aaron, so they did.

29And it came to pass at midnight that the Lord struck all the firstborn in the land of Egypt, from the firstborn of Pharaoh who sat on his throne to the firstborn of the captive who was in the dungeon, and all the firstborn of livestock.

30So Pharaoh rose in the night, he, all his servants, and all the Egyptians; and there was a great cry in Egypt, for there was not a house where there was not one dead.