Writing over previously output lines in the command prompt with ruby

I've run command line programs that output a line, and then update that line a moment later. But with ruby I can only seem to output a line and then another line.

What I have being output now:

Downloading file:
11MB 294K/s
12MB 307K/s
14MB 294K/s
15MB 301K/s
16MB 300K/s
Done!

And instead, I want to see this:

Downloading file:
11MB 294K/s

Followed a moment later by this:

Downloading file:
16MB 300K/s
Done!

The line my ruby script outputs that shows the downloaded filesize and transfer speed would be overwritten each time instead of listing the updated values as a whole new line.

I'm currently using puts to generate output, which clearly isn't designed for this case. Is there a different output method that can achieve this result?