Suicide attack rocks Istanbul
Ambulances rushed to treat the dozens of injured victims on Istiklal Caddesi, a major shopping street in Turkey that runs from the popular Taksim Square.
"This is a suicide attack, a terrorist attack," Istanbul governor Vasip Sahin said, adding that the perpetrator was also killed.
A waiter working in a nearby restaurant told AFP how he had heard "a loud explosion".
"When I came out, people were running in every direction, but I ran towards the blast site to see what happened," he said.
He described "people lying all about, it was carnage".
Health Minister Mehmet Muezzinoglu said 36 people were injured, seven seriously. They included six Israelis along with two people from Ireland and one each from Germany, Iceland, Iran and Dubai, the health ministry said.
CCTV footage circulated by Turkish media showed a man wearing a long coat, reportedly the bomber, approaching a small cluster of people outside a local government building directly before the blast.
"All possible avenues (of investigation) are open," a Western diplomatic source told AFP, noting that the target of the attack could have been either tourists or a symbol of the state.
But German intelligence reportedly warned of the attack, which took place just metres from its consulate in Istanbul, earlier in the week.
German authorities shut the consulate in response - prompting criticism from Turkish press and Istanbul's governor, who accused the EU powerhouse of scaremongering.
But social media users have been taking to Twitter on Saturday, using the hashtag #DankeschönDeutschland, to thank German officials for the warning, saying many more people would likely have been in the Taksim area without the alert.
Last week, a female suicide car bomber with links to Syrian Kurdish rebels killed at least 37 people in Ankara.
Officials, who identified that bomber as Seher Cagla Demir, born in 1992, said she had been affiliated with the outlawed Kurdistan Workers' Party (PKK) since 2013 and then "crossed into Syria and received terror training in the YPG terrorist organisation".
The People's Protection Units, or YPG, is a Syrian Kurdish militia that Ankara regards as a terror outfit with links to the outlawed PKK.
No group has yet claimed Saturday's attack.