tar: Error is not recoverable

Error description:

tar xvf hadoop-3.0.0-src.tar.gz

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

Analyse:

1. The type of file may be incorrect.

2.  Downloaded file didn't correctly completed. 

How to check? by file command 

file hadoop-3.0.0-src.tar.gz
hadoop-3.0.0-src.tar.gz: HTML document text