The Lord said to Moses, "Lift up you rod, and stretch your hand over the sea, and divide it: and the children of Israel shall go on the dry ground in the middle of the sea."
And Moses stretched out his hand over the sea; and the Lord blew a strong wind all the night.
The Red Sea parted and there was a dry path to go...
In the morning the Hebrews started to cross the sea.
They were walking on the dry path, and the huge walls of water were on the both sides of the miracle path...
Egyptians were behind the cloud till almost all the Hebrew people were through. They were waiting for the chance to go.
As soon as the cloud moved away, Pharaoh and his army started after their slaves...
So when all the Hebrews crossed the Red Sea, God told Moses to stretch his hand over the sea, that the waters might come over Egyptians.