The attack in the country's second largest city occurred Thursday evening and the unidentified victims, ages 25 and 26, are believed to be brothers, The Belfast Telegraph, reported Friday.
They were hospitalized and their condition was reported to be life-threatening.
Social Democratic and Liberal Party member of the legislative assembly for the area, Mark Durkan, said there was "no justification" for such violence.
Beautician charged with giving client fatal silicone butt injection
Duggar sisters unveil Christian dating rules in new book