According to Alexander Kazakov, adviser to the DPR head, the suspects have been detained following an operation.
"At this point, a state of emergency has been introduced in the republic, the borders have been closed, suspects have already been detained," Kazakov said in an interview with the television channel Russia-1.
Kazakov added that despite the announced detention of the suspects, the borders of the DPR, including those with Russia and Lugansk People's Republic, are closed as operation is in course.
Following the death of the DPR Head, the deputy prime minister Dmitry Trapeznikov was appointed as Zakharchenko's successor.
"The decision of the DPR territorial defense headquarters: in accordance with the paragraph 1 of the article 102 of the DPR Constitution, to appoint Trapeznikov Dmitry Viktorovich, the deputy head of the council of ministers, interim [DPR] leader in connection to the death of [DPR] head Alexander Zakharchenko," the decision, read out by Trapeznikov himself, read.
Russia's Statements on the Assassination
The President also expressed his deep condolences, that Russia will always be with the people of Donbass.
"I want to express condolences… to relatives and friends of Alexander Vladimirovich Zakharchenko and all people of Donbass. Russia will be always with you," Putin said.
Following the explosion, Russia's Investigative Committee has opened a criminal investigation, considering the incident to be an act of international terrorism, spokeswoman Svetlana Petrenko said.
"Russia's Investigative Committee, based on the existing international experience in the investigation of terrorist acts, is ready to provide all possible assistance to law enforcement agencies of the Donetsk People's Republic in the probe," Petrenko added.
Alexander Zakharchenko, who had been leader of the republic since November 2014, was killed by a bomb in a restaurant in central Donetsk earlier on Friday.