Events leading up to the referendum called by separatists in eastern Ukraine:

April 7: Pro-Russian activists proclaim the creation of the Donetsk People’s Republic.

April 12: Separatists take control of the city of Slovyansk.

April 18: The United States, Russia, Ukraine and the European Union reach a deal for groups to disarm and end occupations of public buildings and spaces across eastern Ukraine.

April 19: Separatists say they will not sign the deal until the new government in Kiev steps down.

April 24: Ukraine sends troops to try to expel the separatists from Slovyansk; five rebels are killed.

April 25: Ukrainian forces mount a full blockade of Slovyansk. Separatists detain a group of international observers, saying a Kiev “spy” is among them.

May 2: Dozens of people are killed in clashes and a fire in Odessa, Ukraine’s third-largest city.

May 7: Russian President Vladi­mir Putin unexpectedly calls for separatists to postpone the referendum.

May 9: A deadly firefight breaks out in the eastern city of Mariupol.

May 11: Pro-Russian activists hold a referendum that they hope will legitimize their movement.

— Staff and wire reports