Her mother was also injured in the incident and was hospitalised with injuries that are not life-threatening.
A man in his 30s was arrested earlier this afternoon and is being held on suspicion of murder.
Eight-year-old Malika Al Kattib died following the incident at her home on Lower William Street on Sunday night.
Her mother was also injured in the incident and was hospitalised with injuries that are not life-threatening.
The attacker was also injured.
He was discharged from hospital earlier this afternoon, before being arrested and taken to a garda station in the southeast of the country.
Meanwhile Gardai believe they have established most of the facts surrounding the incident and are following a definite line of inquiry.
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