ISTANBUL — Turkey is claiming a breakthrough in Sunday's fatal bombing with security forces detaining a woman suspected of planting the bomb that killed six people and injured over 50 others. Ankara is accusing Syrian Kurdish militants backed by the United States of ordering the attack.

In the early hours of Monday morning in Istanbul, Turkish security forces arrested the woman suspected of planting the bombing in Sunday's attack. Turkey's Interior Minister Suleyman Soylu announced what authorities touted as a breakthrough.

Soylu said, "A short while ago, the person who carried out the incident, who left the bomb, was detained by the Istanbul police; 21 other people had been detained."

Arrests are continuing, with more than 50 being held as of early Monday.

Video footage of a woman appearing to leave a bag at the site of the bombing and then running away was released shortly after the attack.

Turkish security forces named the suspect as Syrian national Ahlam Albashir. They claim she has confessed to being trained by the Kurdistan Workers Party, the PKK. The PKK in a statement Monday denied involvement in the bombing, saying it doesn’t target civilians.

So far, no one has claimed responsibility for the attack.

The PKK has been fighting the Turkish state for greater Kurdish rights for more than 40 years. The militant group was linked to the bombing of an Istanbul football match in 2016, killing more than 40 people.

But Soylu, the Turkish interior minister, claims Sundays' attack was organized in Kobani, a Syrian city controlled by the YPG, a Syrian Kurdish militia, which Ankara says is affiliated with the PKK, a charge it denies. The United States backs the YPG in its war against the Islamic State. Soylu speaking at the site of the Istanbul bombing says that Turkey needs to reconsider its ties with its American ally following Sunday's attack.

Soylu said Turkey rejects the condolences of the American Embassy. Turkey, he said, does not accept it. The Turkish official said an alliance with a state that sends money from its own Senate to these groups, feeding the terror zones in Kobani, which aims to disturb Turkey's peace, is — in his words — in a controversial situation. This is open and clear, Soylu said.

Washington's backing of the YPG and its political affiliate, the PYD, is poisoning relations with its Turkish ally, says international relations professor Senem Aydin-Duzgit of Istanbul's Sabanci University.

You have the American alliance with the Kurds, with PYD, in particular in northern Syria. So, there is this perception that America is sort of is an alliance with the PKK and the Kurdish nationalist movement. And that sort of creates kind of hostility as well.

The escalating diplomatic dispute between Turkey and United States comes as shopkeepers clear the devastation of Sunday's bombing and, like the rest of the city, try to come to terms with this latest attack, as shopkeeper Lokman Kalkan explains.

He said, “It has been a disaster, you see. This is all that happened. People were fighting for their lives. There is nothing we can do," he said.

Details of those killed by Sunday's attack are now being released. A mother and son, a father and daughter, and a married couple, the oldest victim was 40. (KB/VOA)