The Myanmar military is carrying out "premeditated" attacks on peaceful protesters - including "extrajudicial executions" and indiscriminately spraying bullets in urban areas, Amnesty International has said.
The human rights organisation has looked at more than 50 videos from the ongoing crackdown on demonstrators opposed to the military coup on 1 February.
It said footage clearly shows Myanmar troops, also known as the Tatmadaw, are increasingly armed with weapons that are only appropriate for the battlefield and not for policing actions.
It also said it has verified multiple clips showing lethal force is being used in a planned, premeditated and coordinated manner.
The 55 clips, filmed from 28 February to 8 March, were recorded by members of the public and local media in cities including Dawei, Mandalay, Mawlamyine, Monywa, Myeik, Myitkyina and Yangon.
One video shows a commander standing over an officer operating a sniper rifle in the Sanchaung township in Yangon on 2 March, Amnesty International has said.
The commander appears to be giving him orders to direct fire towards specific protesters, the human rights organisation added.
A clip from the North Okkalapa township in Yangon shows officers leading a man towards a larger group of security forces.
The man appears to be in the group's custody and offers no visible resistance, when an officer beside him suddenly shoots him.
He immediately drops to the ground and is left on the road, apparently lifeless, for several seconds before officers then walk back and drag him away.
Amnesty International said many of the killings it has seen amount to extrajudicial executions.
One verified clip shows a member of the military in Dawei apparently lending his rifle to a police officer deployed alongside him. The officer crouches, takes aim and shoots, before a group of officers standing with them celebrate.
Verified footage from 1 March in Mawlamyine in Mon State shows security forces riding pick-up trucks while apparently indiscriminately firing live ammunition in multiple directions, including into people's homes.
Amnesty International has identified security forces armed with a variety of military firearms, including Chinese RPD light machine guns, as well as local MA-S sniper rifles, MA-1 semi-automatic rifles, Uzi-replica BA-93 and BA-94 submachine guns, and other arms manufactured in Myanmar.
The human rights group said these weapons are completely inappropriate for use in policing protests.
Joanne Mariner, Director of Crisis Response at Amnesty International, said: "These Myanmar military tactics are far from new, but their killing sprees have never before been livestreamed for the world to see.
"These are not the actions of overwhelmed, individual officers making poor decisions. These are unrepentant commanders already implicated in crimes against humanity, deploying their troops and murderous methods in the open."
The number of dead from the protests stood at 61 as of 4 March, according to the UN Special Rapporteur on the situation of human rights in Myanmar.
State-run media quoted military authorities on 5 March as denying any role in fatalities, claiming that "unscrupulous persons (might be) behind these cases".