John Gill Commentary Exodus 14:9

"And the Egyptians pursued after them, all the horses [and] chariots of Pharaoh, and his horsemen, and his army, and overtook them encamping by the sea, beside Pihahiroth, before Baal-zephon." — Exodus 14:9 (ASV)

But the Egyptians pursued after them
When they thought nothing of it, and had no fears about it:

all the horses and chariots of Pharaoh, and his horsemen, and his army ;
by the latter Aben Ezra understands the foot, as distinguished from the cavalry, the horses and horsemen; and perhaps these, as before observed, might be carried in the chariots for quicker dispatch:

and overtook them encamping by the sea, beside Pihahiroth, before
Baalzephon ;
where they had pitched their camp by divine appointment, (Exodus 14:2) .