The two men, aged 18 and 19, had previously been arrested under the terrorism act, the Police Service of Northern Ireland tweeted.
McKee, a 29-year-old prominent freelance journalist who wrote for publications including The Atlantic and Buzzfeed News, was killed in the Creggan area of Londonderry, also known as Derry, on Thursday night in what police described as a terrorist incident.
The release of the two men comes the same day that Sinn Féin Vice President Michelle O’Neill called on those who brought guns to the streets of Derry to disband and end their actions.
“The people who brought guns onto the street, and those who organize them do not represent any version of Irish republicanism,” O’Neill said at the Easter Commemoration in Derry.
“They have no politics, no strategy, and no popular support amongst the vast number of ordinary people from this city or anywhere else in the country.
“Their actions are a barrier to Irish unity.”
Bishop Donal McKeown, speaking at St. Columba’s Church in Londonderry, also spoke about McKee’s death.
“We pray for all those who are heartbroken at the tragic loss of Lyra. As the dead have slipped through our fingers, we pray trust in the risen Jesus they will be at peace and we will find peace at their passing.”
Journalist was shot amid street violence
On Sunday, detectives from the Police Service of Northern Island asked for anyone who may have information on the killing to come forward.
“We have received very positive support from the community but we need to convert this support into tangible evidence that will enable us to bring Lyra’s killers to justice,” Detective Superintendent Jason Murphy said. “We will continue to work positively and sensitively with the local community to achieve this.”
Thursday night’s violence came ahead of Easter weekend, during which some republicans mark the anniversary of the 1916 Easter Rising, considered one of the most important events in the struggle for Irish independence from Britain.
As the searches began, a crowd gathered and “upwards of 50 petrol bombs were thrown at officers,” the statement said. Two vehicles were hijacked and set on fire, it added.
McKee was standing close to a police vehicle when she was wounded by the shots fired by a single gunman. She died soon after from her injuries, Assistant Chief Constable Mark Hamilton told reporters on Friday.
Police release surveillance footage
Police said the shooting was carried out by dissident republicans, namely the New IRA. Murphy said Saturday that he believed the two teenagers who were arrested were members of the New IRA and were involved in the attack.
“Lyra was killed by shots that were fired indiscriminately,” he said. “The gunman showed no thought for who may have been killed or injured when he fired these shots.
“I know there will be some people who know what happened but are scared to come forward. I want to reassure you that we will work with you sensitively.”
In addition, the PSNI released footage of the shooting in the hope that members of the public would provide information to assist the investigation into McKee’s killing.
McKee, who was born in Belfast, is the first journalist to be killed in the United Kingdom since 2001, according to nonprofit organization the Committee to Protect Journalists.
During a vigil on Friday, her partner, Sara Canning, said McKee’s “amazing potential was snuffed out by this single barbaric act.”
“Victims and LGBTQIA community are left without a tireless advocate and activist and it has left me without the love of my life, the woman I was planning to grow old with,” she added.
“This cannot stand. Lyra’s death must not be in vain because her life was a shining light in everyone else’s life and her legacy will live on and the life that she has left behind.”
In a rare joint appearance Friday, Democratic Unionist Party leader Arlene Foster and Irish republican Sinn Fein party leader Mary Lou McDonald condemned the killing.
CNN’s Eric Levenson contributed to this report.