TIRUVARUR: In what is said to be part of the investigation into the Coimbatore car blast case, the police on Saturday raided the residences of four at Muthupettai in the district. A team led by Muthupettai DSP T Vivekanandhan raided the houses of Riswan Muhamed, Ahmed Imtiaz, Sajid Ahmed and Azharuddin in the wee hours. All four are said to have been detained a few years ago over suspicions of links to terror outfits.