How do the first two paragraphs of The Adventures of Tom Sawyer indicate that the narrator is using a third-person omniscient point of view?

From the text:

Most of the adventures recorded in this book really occurred; one or two were experiences of my own, the rest those of boys who were schoolmates of mine. Huck Finn is drawn from life; Tom Sawyer also, but not from an individual—he is a combination of the characteristics of three boys whom I knew, and therefore belongs to the composite order of architecture.

“TOM!” No answer.

“TOM!” No answer.

“What’s gone with that boy, I wonder? You TOM!”

No answer.

The old lady pulled her spectacles down and looked over them about the room; then she put them up and looked out under them.

The narrator provides the dialogue and also speaks about Aunt Polly, describing her as she walks about the room. The narrator is not a part of the story, but the narrator is also omniscient (all knowing) about the activities of the characters.