The deceased Linesh and four others were allegedly engaged in making crude bombs at a vacant place when the explosion took place around 9.30 PM near Thiruvamparambu in the district on April 27.
Linesh along with others injured were admitted to the hospital.
Another seriously injured person is out of danger, police said.
Cases under Sections 3 and 5 of Explosive Substances Act had been registered against them, they said.