 -- A morning car bomb in southeast Turkey's Kurdish region killed nine people and injured more than 100, while the arrests of several pro-Kurdish lawmakers hours before caused strife across the European Union.

A minibus carrying what police estimate to be a ton of explosives detonated in the city of Diyarbakir, the largest city in Turkey's Kurdish southeast region, where a police building and nearby businesses were severely damaged.

Two policemen and seven civilians, including the suicide bomber, were killed. A passing taxi driver alerted crowds of the threat when he realized there was a bomb in the minibus, which helped the casualty number to stay low.

The Kurdistan Workers' Party, or PKK, which has been the source of several recent bombings in Turkey and is considered a terror organization, has taken responsibility.

Before the attacks, authorities detained at least 12 people on terrorism-related charges, including five pro-Kurdish lawmakers, causing tensions among Turkish citizens and E.U. lawmakers alike.

In a statement from the European Union, High Representative-Vice-President Federica Mogherini and Commissioner Johannes Hahn said they were "gravely concerned" about the detentions, adding they "compromise parliamentary democracy in Turkey and exacerbate the already very tense situation in the South East of the country."

While the E.U. considers PKK a terrorist group, it believes that actions taken against organization "must never undermine the basic principles of democracy."

People's Democratic Party (HDP) co-chairs Selahattin Demirtas and Figen Yuksekdag were among the detained, and the HDP called it a "dark day" for Turkey in a news release.

Calling President Recep Tayyip Erdogan's policies authoritarian, the release stated, "There is no freedom of expression and no freedom of press, no academic freedom, and no fair and independent judicial system anymore."

Since the arrests, protesters demonstrating against the detentions have been met with tear gas and water cannons in the cities of Istanbul, Ankara, Izmir and Antalya.