Oh, interesting. The article doesnt really imply any Indian government connection. Two of the 3 have surnames Singh, so they are likely Sikh themselves. So the Indian government version that its just a Canadian Sikh gang seems plausible, based on this article at least. I'm waiting for more info.
There are tons of Sikhs loyal to the indian government; the last-name proves nothing.
Some of the generals involved in the golden temple incident were Sikh and all Sikh soldiers had right to refuse to participate but none did so.