Myanmar security forces on Saturday killed at least 90 people in anti-coup protests, several news agencies reported.

Why it matters: It's the bloodiest day of protests since the military last month overthrew the country's democratically elected government and comes as Myanmar’s military celebrates the annual Armed Forces Day holiday with a parade in the country's capital, Naypyidaw.

Context: Protesters have congregated in cities across the country for almost two months, demanding that democracy be restored.

• The military junta now running the country has repeatedly used leathal force against civilians to maintain power.

What they're saying: During the armed forces parade, Senior Gen. Min Aung Hlaing, the chief of the junta now in control of the country, claimed that the military would protect the people and strive for democracy, according to Reuters.

• However, state television warned protesters on Friday night that they risked being shot “in the head and back” if they demonstrated during the national holiday.

U.S. Ambassador Thomas Vajdasaid in a statement Saturday that "security forces are murdering unarmed civilians, including children, the very people they swore to protect."

• "This bloodshed is horrifying. These are not the actions of a professional military or police force. Myanmar’s people have spoken clearly: they do not want to live under military rule. We call for an immediate end to the violence and the restoration of the democratically elected government," he added.

The big picture: The deaths on Saturday increase the number of civilians reported killed by security forces since the coup to well over 400.

• Thousands more civilians have been arrested, including a number of journalists.