Exodus 12:29-39 NIV
At midnight the LORD struck down all the firstborn in Egypt, from the firstborn of Pharaoh, who sat on the throne, to the firstborn of the prisoner, who was in the dungeon, and the firstborn of all the livestock as well. Pharaoh and all his officials and all the Egyptians got up during the night, and there was loud wailing in Egypt, for there was not a house without someone dead.
During the night Pharaoh summoned Moses and Aaron and said, “Up! Leave my people, you and the Israelites! Go, worship the LORD as you have requested. Take your flocks and herds, as you have said, and go. And also bless me.”
The Egyptians urged the people to hurry and leave the country. “For otherwise,” they said, “we will all die!” So the people took their dough before the yeast was added, and carried it on their shoulders in kneading troughs wrapped in clothing. The Israelites did as Moses instructed and asked the Egyptians for articles of silver and gold and for clothing. The LORD had made the Egyptians favorably disposed toward the people, and they gave them what they asked for; so they plundered the Egyptians.
The Israelites journeyed from Rameses to Sukkoth. There were about six hundred thousand men on foot, besides women and children. Many other people went up with them, and also large droves of livestock, both flocks and herds. With the dough the Israelites had brought from Egypt, they baked loaves of unleavened bread. The dough was without yeast because they had been driven out of Egypt and did not have time to prepare food for themselves.
NIV: New International Version