Gunmen who shot dead two soldiers and a police officer in the North have committed crimes against humanity, a peace rally in Belfast was told today. Thousands gathered for vigils organised by trade unions at venues across the North at 1pm to demand an end to the renewed violence. The crowds gathered outside Belfast City Hall observed a minute's silence in memory of the security forces killed in separate attacks by dissident republicans. Constable Stephen Carroll was shot dead by the Continuity IRA in Craigavon, Co Armagh, on Monday night and soldiers Mark Quinsey, 23, and Patrick Azimkar, 21, were shot by the Real IRA at Massereene Army barracks in Antrim on Saturday night. After a piper played Abide With Me, trade union leader John Corey told the Belfast rally that the public rejected any return of violence. ``The trade union movement has always stood for peace,'' he said. ``For this movement, no political cause in Northern Ireland justifies violence of any kind. Police today continued to question a 37-year-old man and 17-year-old youth about the murder of Constable Carroll. They were arrested yesterday as police carried out searches in the Drumbeg estate which overlooked the small residential cul-de-sac where he died while answering a call from a distraught woman who had a brick thrown through her window. Rallies were also held today in Derry, Newry, Lisburn and Downpatrick, with impromptu rallies also organised by trade unionists south of the border. Sympathies were expressed for the families of the murdered soldiers, as well as the relatives of Constable Carroll as they prepare to lay him to rest on Friday after noon Requiem Mass at St Therese Church in Banbridge, Co Down. There were emotional scenes as the officer's widow Kate tonight watched as a police escort brought her husband's body back to the couple's Banbridge home. As people gathered in their thousands to demonstrate against violence, the same message was delivered by British Prime Minister Gordon Brown in the House of Commons and by Taoiseach Brian Cowen in Dublin. Mr Brown told MPs: ``The peace marches today on the streets of Northern Ireland show what I saw in Northern Ireland on Monday and what we are seeing right across the country. ``The unity against violence of the people and their representatives; the defiance and the determination to stand up to the evil and criminal violence; and the unyielding resolution to say with one voice that the peace that the people of Northern Ireland are building no murderers should ever be allowed to destroy.'' Taoiseach Brian Cowen told the Dail, where TDs backed an all-party motion against the violence, that co-operation between police on both sides of the border had never been closer. Earlier today the Pope denounced the murder of the three security force members as ``abominable acts of terrorism''.