At least 18 people were killed and 30 injured across Myanmar on Sunday after the police opened fire to curb protests against the military coup, the United Nations Human Rights Office said.

“Throughout the day, in several locations throughout the country, police and military forces have confronted peaceful demonstrations, using lethal force and less-than-lethal force that – according to credible information received by the UN Human Rights Office – has left at least 18 people dead and over 30 wounded,” the UN department said.

The department added: “Deaths reportedly occurred as a result of live ammunition fired into crowds in Yangon, Dawei, Mandalay, Myeik, Bago and Pokokku. Tear gas was also reportedly used in various locations as well as flash-bang and stun grenades.”

The police also threw stun grenades outside a medical school in Yangon, Reuters reported. A medics’ body called Whitecoat Alliance told the news agency that 50 medical staff members had been arrested.

Also read: How Myanmar security forces are using night raids to suppress protests against the coup

Sunday Times’ Asia correspondent Philip Sherwell told France24 that this was “the bloodiest day of this month-long uprising against the coup”.

The UN Human Rights Office called on the Myanmar military to immediately stop violence against peaceful protestors. “Use of lethal force against non-violent demonstrators is never justifiable under international human rights norms,” it added. The military had also imposed internet blackouts to control the growing protests.

The coup in Myanmar on February 1 followed the landslide victory of National League for Democracy and Aung San Suu Kyi in national elections in November, with the military-backed Union Solidarity and Development Party faring poorly in its key strongholds.

The country’s military refused to accept the government, citing unsubstantiated allegations of fraud. It was also announced that the coup was the result of the government’s failure to delay the November election despite the outbreak of the coronavirus. Suu Kyi was detained after the military seized power.