“Shocking footage from Istanbul.
My thoughts and deepest condolences to all the victims and the Turkish people.
NATO stands in solidarity with our ally Turkey,” he tweeted.
The explosion occurred during the day on the pedestrian street Istiklal.
The Prosecutor General's Office of the city opened a criminal case, the version of the attack is being considered.
According to the latest reports, six people died.
There were no Russians among the victims.
In total, 81 injured citizens were reported, two people are in serious condition.
Turkish President Recep Tayyip Erdogan stressed that the explosion in Istanbul "smells like a terrorist attack."