CHENNAI: With the risk of coronavirus spreading further in densely populated cities, Tamil Nadu Chief Minister K. Palaniswami on Friday ordered tightening of the lockdown in Chennai, Coimbatore, Tiruppur, Salem and Madurai.The decision was taken after Palaniswami chaired a review meeting on the coronavirus spread in the state.In a statement issued here, Palaniswami said in Chennai, Coimbatore and Madurai the lockdown will be implemented strictly between 6 a.m. and 9 p.m. from April 26-29.He said in the case of Tiruppur and Salem the lockdown will be between 6 a.m. to 9 p.m. from April 26-28.According to him, sanitisation of containment zones will be done twice a day in the state.He said only work from home is permitted for software companies and other private companies should not function in these five districts.The Chief Minister also ordered the closure of registration department offices while allowing only the following to function:- Hospitals, diagnostic test labs, pharmacies, ambulance and hearse services;- Essential services departments in the state secretariat, health, revenue, disaster management, electricity, milk, water supply departments;- Other central and state government offices with 33 per cent staff strength;- Government run Amma Canteens, ATMs;- Old age homes and orphanages;- Community kitchens run by district/local administrations;- Service organisations for the benefit of poor with government permission and- Vegetable markets, mobile vegetable shops will run subject to regulations.On Friday, the death toll in Tamil Nadu due to Covid-19 went up to 21, with one senior citizen breathing her last in Madurai, said officials.