Undertaker had first and second degree burns on his chest and neck. Those within WWE consider him very lucky, having escaped with the burns he had, as opposed to how badly it could have been.
Despite the burns, Undertaker continued to work through the match in tremendous pain, and even refused to shorten the match. The sleeve of his jacket and part of his hand had melted when the pyro went off prematurely.
There was talk of having Shawn Michaels take responsibility for the pyrotechnics incident that happened at the Elimination Chamber PPV. The decision was made prior to RAW, and that idea was ultimately shot down.
One of the key things in the decision making was going to be based off how their camera angles had the incident, if it came off impressive, the idea would have been used on TV.
(Credit to F4wonline.com for some of the news used in this report)