The Ferguson police officer who fatally shot Michael Brown has resigned, his attorney said Saturday, nearly four months after the confrontation between the white officer and unarmed black 18-year-old that ignited protests in the St. Louis suburb and across the nation.

ERGUSON, Mo.—Nearly 20 people have been arrested during a large rally to protest the killing of 18-year-old Michael Brown in Ferguson, Missouri.

Thousands have gathered in St. Louis for a second day of rallies and marches protesting Michael Brown’s death and other fatal police shootings.

Tense but peaceful protests over Michael Brown’s death and other fatal police shootings in Missouri and elsewhere stretched across the St. Louis region Friday as organizers urged hundreds of participants to avoid arrest so that they could return for a weekend of demonstrations.