ANKARA, Turkey (AP) -- Turkish authorities on Friday detained three more suspects in connection with the deadly bombing in Ankara that Turkey has blamed on Kurdish militants at home and in neighboring Syria, while Turkey's military pushed ahead with its cross-border artillery shelling campaign against U.S.-backed Syrian Kurdish militia positions in Syria.
Anadolu Agency said authorities have now taken 17 people into custody as part of the investigation into Wednesday's attack, which targeted buses carrying military personnel. Anadolu said the latest suspects are believed to be linked to the outlawed Kurdistan Workers' Party, or PKK.
Anadolu also reported late Thursday that artillery units were "intermittently" firing shells into Syria, targeting militia positions near the village of Ayn Daqna, south of the town of Azaz.
Prime Minister Ahmet Davutoglu said the suicide car bomb attack that killed 28 people on Wednesday was carried out by a Syrian national who was a member of the People's Protection Units, or YPG. He said rebels of the PKK, which has led a more than 30-year insurgency against Turkey, were also behind the attack.
The leader of the main Syrian Kurdish group, Salih Muslim, however, has denied his group was behind the bombing, and he warned Turkey against taking ground action in Syria.
Following the attack, Turkey stepped up pressure on the United States and other allies to cut off support to the militia group. Turkey views the YPG as a terror group because of its affiliation with the PKK.
The YPG, however, has been most effective in the fight against the Islamic State group in Syria.
Ankara appears increasingly uneasy over the group's recent gains across its border and has continued to shell the militia despite international calls for it to stop.
Davutoglu, accompanied by other ministers, placed 28 carnations at the site of the attack Friday in honor of the dead. Hundreds of people, meanwhile, filled two main mosques in Ankara for the funerals of at least eight of the victims.
The attack was the second bombing in the capital in four months.