No one has claimed responsibility at this point. [1] We have seen jihadists target tourists in Egypt before. "Tourists hit by Cairo bomb blast," from the [2] BBC, February 22 (thanks to Larry):

A bomb explosion in Cairo has killed at least one person and injured 17 others, mostly foreign tourists, police say.

The dead person was identified as a French tourist. An unconfirmed report from Reuters news agency said there were four dead, two of them foreigners.

The blast happened outside a cafe packed with French tourists in the historic Khan al-Khalili area.

The explosion was relatively small, most likely caused by a home-made explosive device, police believe....