Although the lead message ridiculed the idea of massive carnage - there never had been a claim of massive carnage. No deaths were claimed from this bombing.
Only two people were seriously hurt, but about 22 people had minor injuries and were sent to a hospital only a block away. Although I haven't found a news report providing more details, it is possible that some of those with minor injuries were OUTSIDE the bus and hit by shards of window glass from the explosion.