Burglars broke into ATMs at four different places in Tiruvannamalai in one night on Saturday, allegedly looting over Rs 50 lakh.
Of the four ATMs, three belong to SBI and one belongs to India One, police sources said.
The three SBI ATMs are located in Mariamman Kovil, Theni malai, and Polur railway station, and the India One ATM at Kalasapakkam.
The burglars used a gas-welding machine to break open the ATM. Even a machine got burnt during the looting, the sources said.
The police, on information, rushed to the spot and launched an inquiry.
The police were checking the footage of CCTVs that were installed in and around the ATM centres and in surrounding areas.
The police have special teams under the direct monitoring of Superintendent of Police K. Karthikeyan. Vellore range Deputy Inspector General of Police (DIG) M.S Muthusamy and other senior police officers were carrying out the investigation.
Fingerprint experts had collected samples from the crime spots and sent them for analysis.
The police were holding the probe to establish the identities of the robbers and how many were involved in the overnight burglary.