Four persons were injured when a country-made bomb exploded in a residential area on Saturday, sparking tension in this temple town in Tamil Nadu, which is on high alert after the twin blasts on Kaziranga Express in Chennai on Thursday that claimed a woman’s life.

The incident occurred in a room located above a medical shop here, and one person, identified as Arul and working in a prominent university, was among four who sustained serious injuries, police said.

The incident created panic among locals as it came two days after the blast on the Bangalore-Guwahati Express at the Central railway station in Chennai in which a 24 year-old techie was killed and 14 others were injured.

The State is on a high alert following the May day explosion.