Seven people have been booked for the killing of a JD(S) worker, that has erupted into a big political row after Chief Minister H D Kumaraswamy's call to "shoot" the killers "mercilessly".

Old rivalry or a political motive may be behind the killing, Additional Superintendent of Police Mandya District Balaramegowda told PTI.

"We have not arrested anyone yet. Investigations are on. We have registered an FIR against seven suspects," he said.

The ASP said the suspects have been booked under section 302 (murder) and 307 (attempt to murder) of the Indian Penal Code.

"Old rivalry seems to be the motive; there may also be a political motive," he said.

Prakash was hacked to death on Monday evening allegedly by four men in Maddur town of Mandya district, which is a JD(S) stronghold. The killing sparked tension in and around Maddur as the victim's supporters and party workers staged a protest by blocking a road.

Kumaraswamy found himself in a raging controversy Tuesday after a video of his telephonic instruction to "shoot mercilessly" those who had killed a JD(S) worker in the party's stronghold of Mandya district on Monday went viral.

In the video, Kumaraswamy was heard saying: "I don't know how you will handle it (the case).. because it was your responsibility. I am actually disappointed because it (the murder) brought a bad name."

"He (Prakash) was a good person...There is no problem if you shoot such people mercilessly," he said alluding to the alleged killers.

"I am least bothered (about the consequences)," the chief minister had said.

He, however, rejected the opposition demand for an apology over his comments, saying he was an "emotional person."

"It is not a big issue..it is a human tendency...in that sort of a situation, any human being will react like that. I have already clarified it, that is why I changed the word also," Kumaraswamy said.