Scores of supporters have gathered outside the hospital where prayers are being offered for the speedy recovery of the CM.
The police have had a tough time in controlling the crowd which gathered in large numbers after the news regarding the cardiac arrest broke.
Barricading was done at the hospital area in Chennai to keep a check on the crowd.
Nine companies of the Rapid Action Force has been put on stand-by.
Each RAF company comprising 100 security personnel are ready to be airlifted and stationed in various parts of Tamil Nadu if the need be.
Several police personnel had gathered outside the Rajarathinam stadium.
Several police personnel were seen outside the stadium getting ready for deployment.
The state of Tamil Nadu has been put on high alert and is likely to resemble a fortress all through the day today.