At midnight the LORD struck down all the first offspring in the land of Egypt, from the oldest child of Pharaoh sitting on his throne to the oldest child of the prisoner in jail, and all the first offspring of the animals.
References for Exodus 12:29
When Pharaoh, all his officials, and all the Egyptians got up that night, a terrible cry of agony rang out across Egypt because every house had someone in it who had died.
Then Pharaoh called Moses and Aaron that night and said, "Get up! Get away from my people, both you and the Israelites! Go! Worship the LORD, as you said!
You can even take your flocks and herds, as you asked. Just go! And bring a blessing on me as well!"