And, as the singing began, all the people who were in the pews within the wall came out of them and streamed through the archway into the nave. They took what places they could find up and down the church, and the rest of the congregation looked at them in amazement.
This is from "The Great Return" by Arthur Macken.
I don't undestand the meaning of the sentence below.
They took what places they could find up and down the church,
I am glad if someone would kindly teach me.