Four killed in explosion at Maidan anniversary rally in Kharkow (VIDEO)

At least four have reportedly been killed and 15 injured in an explosion in Ukraine's second-largest city of Kharkiv during a march on the one-year anniversary of Maidan protests Sunday.

"According to preliminary information, around 10 people were injured, one of them a police officer. Two people died on the spot," Ukrainian Interior Ministry said in a statement. According to one of the witnesses cited by Ukrainian TV, the explosion went off immediately after the column of demonstrators started moving toward the city's central Independence Square. One of those killed is reportedly a policeman.

A probe would be opened into an apparent "terrorist attack", local police spokesperson Natalia Zakharova said.

As it has been already reported Ukrainian State Security Service had detained four people suspected. As we have seen it several times before: Ukraine doesn't need any investigation. As it was when MH-17 had been downed in July 2014. As we have already seen it in Volnovakha checkpoint when the passenger bus had been shot.