CNN would report in their article, "30 killed in bombing near main train station in Turkey's capital," that:

At least one powerful bomb hit near the main train station in the Turkish capital Saturday morning, killing 30 people,authorities said, making it the deadliest attack in Ankara in recent memory.

It would also claim that:

No group has yet claimed responsibility for the attack, though suspicion immediately fell on the ISIS terrorist group or on Kurdish separatists in Turkey. 

Turkey avoided, for quite some time, any conflict with ISIS, perhaps in exchange for the release earlier this year of dozens of Turkish hostages seized in the Iraqi city of Mosul. No details of those negotiations have been released. 

However, Turkey recently changed its stance and allowed the U.S. to launch strikes on ISIS from the Incirlik Air Base in southern Turkey.

While CNN attempts to portray Turkey as holding a generally hostile stance toward the so-called "Islamic State" (ISIS), it finally admits toward the end of its report that:

New reports have said that many Turks have joined ISIS' ranks and that Turks, many of whom have been recruiting in Ankara, may make up a third of ISIS' ranks.