Turkish authorities said Monday that a Syrian woman who was detained in connection with a deadly blast in Istanbul was trained by Kurdish militants, though they are not ruling out ties to the so-called Islamic State (IS) terror group.

An official told Reuters the initial investigation revealed the Syrian woman had connections to the Kurdistan Workers Party (PKK). The US and the EU have designated the group a terrorist organizations, subjecting it to financial and other sanctions.

Turkish television broadcast footage of the woman with her face down on a carpet in a private home where she was said to be hiding. In the home, police revealed they uncovered cash, gold items and a gun.

She was later seen being escorted into a police station wearing dark pants and a purple hooded sweatshirt.

What have Turkish authorities said so far?

Interior Minister Suleyman Soylu said the Istanbul police had detained the woman "a little while ago." He added evidence pointed toward the involvement of the Syrian Kurdish group, the Democratic Union Party, or PYD. Turkish authorities see the PYD as an extension of the PKK in the Kurdish regions of northern Syria.

The minister also attacked Washington for its support for Kurdish groups, adding that a condolence message from the White House was akin to a "killer being first to show up at a crime scene."

The US condemned the "act of violence," and added, "We stand shoulder-to-shoulder with our NATO ally in countering terrorism."

Istanbul police also said 46 people had been detained in connection with the blast that left at least 6 people dead.

What happened in Sunday's bomb attack in Istanbul?

A bomb exploded on Istiklal Street, a prominent promenade just off the central Taksim Square in the heart of Istanbul's central Beyoglu district, in the middle of the afternoon at 4:20 p.m. (1320 GMT) local time.

Video taken at the time of the incident showed a huge fireball engulf the normally busy street. Online videos immediately following the blast revealed several bodies, many bloodied, on the street as friends and family gathered around some of the injured, seeking help from paramedics arriving on the scene.

Between 2015 and 2017, Turkey was hit by a wave of terror attacks, some of which were carried out by the Islamic State group. In 2016, a suicide bomber detonated on the same street as Sunday, killing four and injuring 39.