Russian forces were laying mines in areas where they were either expelled from or left on their own in the north of the country, according to Ukrainian President Volodymyr Zelenskyy.
Zelenskyy said in an address that a complete disaster and many dangers are left after them. They are mining all the territory. The bodies of people killed in mining houses. Too many tripwire mines, too many other dangers.
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Zelenskyy told people to wait until the explosives are cleared.
The seven humanitarian corridors are expected to open on Saturday.
The International Committee of the Red Cross was unable to reach Mariupol on Friday.
In a statement, the ICRC said a team of three vehicles and nine personnel were unable to reach Mariupol to facilitate the safe passage of civilians and had to return to Zaporizhzhia.
According to NBC News, another six humanitarian corridors are expected to be opened on Saturday.
The Ukrainian government has accused Russian forces of disrupting the safety of those trying to flee or aid workers delivering necessary supplies by laying mines along humanitarian corridors.
Oleksandra Matviychuk, chair of the Center for Civil Liberties, a Ukrainian humanitarian organization, previously told Insider that her organization has been mainly focused on tracking which corridors are open and safe.
The corridors are not open on some days.
The Office of the UN High Commissioner for Human Rights reported on Friday that 1,325 people have been killed in Ukraine and another 2,017 have been injured since Russia invaded the country on February 24.