ISTANBUL -- The strictest lockdown declared so far since the beginning of the pandemic to curb COVID-19 in Turkey began on Thursday at 7 pm local time (1600 GMT).

Intercity travel is banned except for compulsory cases, and all commercial businesses are closed, with several exceptions, during the complete lockdown which will last until May 17.

With the start of the restraint, security forces started patrolling the empty streets and squares in Turkey's biggest city, Istanbul, establishing over 300 checkpoints.

Additional security forces have also been deployed at the entrances and exits of the city.

Istanbul Governor Ali Yerlikaya said more than 400 gendarmerie forces and nearly 3,000 police officers would be on constant duty across the metropolis.

Meanwhile, many Istanbulites have left the city, either going to their summer houses, hometowns in smaller cities, or hotels in resort towns.

Istanbul Provincial Health Director Kemal Memisoglu warned that those who will spend the lockdown outside the city should be on high alert about the social distancing rule.

The director also noted that the number of COVID-19 cases in Istanbul with a population of over 16 million has decreased by 30 percent in the last 10 days.

The daily number of patients who are discharged is more than those who are under treatments in hospitals, including intensive care units, according to Memisoglu.

Turkey has long been striving against the increasing number of COVID-19 cases on a daily basis despite the ongoing mass vaccination program which started in mid-January.