CBS 4
".... Witnesses told police they thought the assault was racially-motivated but police determined the incident was not..."

"...According to the affidavit, the Hispanic man walked up to the victim and said something but the victim could not hear what was said due to the noise of the crowded bus. Later, the other suspect, described in the affidavit as a white man, walked up to the victim and told him he needed to “shut the (expletive) up.”...

http://denver.cbslocal.com/2017/08/31/rtd-bus-will-kee-dericon-steel-south-high-school/