At least seven people have died in Friday's clashes Ukraine's port city of Mariupol, according to local officials.

The injured were 39, according to the healthcare department at Donetsk's administration.

Latest data comes amid conflicting reports on the incident in the south Ukrainian city.

Ukraine's Interior Ministry had earlier said that twenty pro-Russian protesters and a Ukrainian security officer lost their lives in a gun battle that followed activists' attempt to seize a police headquarters building.

Local officials put the death toll of the attack at seven people and says 39 were injured and this was later spread on by Ukrainian news agencies.

Some witness accounts suggest it was the Ukrainian forces who first opened fire. The Ministry, however, claims that demonstrators, who were reportedly representatives of the self-proclaimed "Donetsk People's Republic", initially took over the first floor of the police building.

Tensions remained high in the city after the incident. Mariupol City Hall, which was a scene of clashes between Kiev soldiers and pro-Russian separatists, both seeking to gain ground, caught fire on Friday night and was still ablaze on Saturday morning.

The reasons for the incidents are yet unknown, according to Ukraine's UNIAN agency.

Ukraine's Interior Minister Arsen Avakov reported on Facebook that Mariupol's police chief has been abducted by activists, but the information has not had further confirmation.

He also argued people with sniperes had been shooting at soldiers and civilians from the roof of the city hospital.

Unrest also continued in other towns and cities across the east of Ukraine. In Donetsk seven Red Cross employees were taken hostage after the organization's headquarters was stormed by unknown perpetrators. One of the kidnapped is French and six Ukrainain, with three having traveled from Kiev to bring medicaments.

RIA Novosti later reported the hostages had been freed and explained they had first been considered spies by “federalization supporters”.

The latest developments in the south and east of Ukraine come as pro-Russian separatists across Donetsk and Luhansk who have seized a number of government buildings are preparing for a referendum on Sunday that should determine their regions' status within the country.