Police said the deceased Kiliammal (75) of Irunkundrapalli village near Chengalpattu was a daily wage labour.
Around 9 pm, Kiliammal was crossing the Chennai-Tiruchy National Highway at Chengalpattu after returning from work when a truck carrying sand knocked her down. Kiliammal was thrown away and died on spot.
Her body was sent to the Chengalpattu government hospital for post-mortem examination.
The Chengalpattu taluk police have registered a case and a search is on for the truck driver.