All 13 people taken hostage on a bus in western Ukraine by a man armed with guns and a grenade were freed on Tuesday evening after a standoff with police ended without casualties, Interior Minister Arsen Avakov said.

Police have arrested the suspected hostage taker, whom the state security service (SBU) identified as 44-year-old Maksym Kryvosh. Avakov said Kryvosh had served time in prison and the SBU said had propagated "extremist views."

In a surreal twist to secure the hostages' release, President Volodymyr Zelenskiy said he spoke to Kryvosh by phone and agreed to one of his demands, to promote the 2005 animal rights documentary "Earthlings," narrated by Hollywood actor Joaquin Phoenix.

Zelenskiy did so in a six-second clip posted on the presidential Facebook page, which was subsequently deleted.

"I congratulate all those who fought all day for the release of the people in Lutsk and, in fact, for their lives," Zelenskiy said in a statement after the hostages were freed.

The SBU published a picture of Kryvosh sprawled on the ground with security personnel standing over him after his arrest. Avakov said an accomplice of Kryvosh was detained in the eastern city of Kharkiv.

(With input from Reuters)