By Agence France-Presse
The 18 and 19-year-olds were arrested in Londonderry under anti-terror laws and taken to Belfast for questioning, the Police Service of Northern Ireland said.
Journalist Lyra McKee was shot in the head late Thursday in Derry by, police believe, dissident republicans linked to the New IRA paramilitary group as they clashed with police on the Creggan estate in Northern Ireland's second city.
Tributes to the 29-year-old were led by her partner, Sara Canning, who said McKee's "amazing potential was snuffed out by this single barbaric act".
Detectives hunting the gunman had released footage of the unrest, hoping that the community would help trace her killers.
Belfast-born McKee, 29, had posted an image from the riots, accompanied by the words "Derry tonight. Absolute madness".
Images of the unrest on social media showed a car and van ablaze and hooded individuals throwing petrol bombs and fireworks at police vehicles.
Police chief Mark Hamilton said Friday "a single gunman fired shots in a residential area of the city and as a result wounded Ms McKee".
Some officials blamed Thursday's unrest on the "New IRA", a republican paramilitary group opposed to the shift towards non-violent tactics to bring about a united Ireland.
The Saoradh party denies being the political wing of the New IRA (Irish Republican Army).
Saoradh said Friday that "heavily armed" police went in to Creggan "to attack republicans in advance of upcoming Easter Rising Commemorations".
"The inevitable reaction to such an incursion was resistance from the youth of Creggan," added the statement.