A 56-year-old traffic sub-inspector was killed in an accident after a concrete mixer lorry rammed his two-wheeler on Kathipara grade separator on Thursday.
On Thursday morning, Natraj was returning home on his two-wheeler from Nandambakkam after work.
When he was on Kathipara grade separator, a concrete mixer lorry rammed his two-wheeler and Natraj died on the spot. The lorry driver fled from the spot, said the police.
The St Thomas Mount traffic police arrived there and sent the body for post-mortem examination to Chromepet Government Hospital.
After a search, the police arrested the lorry driver, Sathish (37) of Kumbakonam, in the afternoon, said sources. The police said that the SI was wearing a helmet but it fell off when the lorry hit his vehicle. The Mount traffic police have registered a case and are investigating.