Istanbul suicide bombing

A man leaves at carnations at the Saturday explosion site in Istanbul, Sunday, March 20, 2016.

A tourist looks at carnations and messages left by people at the Saturday explosion site in Istanbul, Sunday, March 20, 2016.

A man leaves carnations at the Saturday explosion site in Istanbul, Sunday, March 20, 2016.

A man stands in front of the Saturday explosion site in Istanbul, Sunday, March 20, 2016.

Police secure the area as forensic investigators inspect the blast site following a suicide bombing in a major shopping and tourist district in Istanbul on March 19, 2016.

Police secure the area as forensics investigators inspect the blast site following a suicide bombing in a major shopping and tourist district in Istanbul on March 19, 2016.

Turkish policemen cordon off a street after a suicide bomb attack in Istanbul on March 19, 2016.

People leave flowers and pay respects to victims at the site of a fatal blast in Ankara on March 19, 2016. The memorial occurred on the same day as a suicide bombing in Istanbul.