LONDON (AP) — Hundreds of people have gathered in Northern Ireland to mark 50 years since “Bloody Sunday,” one of the deadliest days in the conflict known as The Troubles. Thirteen people were killed and 15 others wounded when British soldiers fired on civil rights protesters on Jan. 30, 1972, in the city of Derry, also known as Londonderry. Relatives of those killed and injured half a century ago took part in a remembrance walk Sunday, retracing the steps of the original march. Crowds gathered at the Bloody Sunday Monument, where political leaders laid wreaths in a ceremony. Prime Minister Boris Johnson told Parliament on Wednesday that Bloody Sunday was “one of the darkest days in our history” and that the country “must learn from the past.”