The gang had also attacked another man who came to the woman's rescue.
Both the woman and man suffered serious injuries and had been admitted to the Government Rajaji hospital at Madurai.
Police said the gang had attacked the woman and tried to snatch her ten-sovereign chain even as devotees, who were returning after offering prayers at the Madapuram Kaliamman temple, were coming behind her.
People raised an alarm and informed the police, which arrested the gang members after a hot chase in a nearby dry river bed.