He heard a sound as if it were being bolted or fastened on the inside.

Then he heard the slamming of another door and a muffled, metallic sound as of someone locking it on the outside.

Then he heard footsteps, fainter, fainter....

Then he heard a sound which seemed to him familiar.

He could not liken it to anything in particular, but it sounded familiar, a kind of clanking, metallic sound.
Then he heard a voice say, "Let me handle her, give her a shove, hold her down, that's right." Pee-wee's blood ran cold.