Authorities have said that Amrani threw three grenades and opened fire in a crowded Belgian square on Tuesday. Amrani was on his way to answer to police questions regarding a prior conviction.
Police believe Amrani went to the Saint-Lambert square where children and adults were attending an annual Christmas event and threw three grenades into the crowd. He started opening fire afterward.
Witnesses said that Amrani shot himself after the whole ordeal. However, police are still investigating whether the lone gunman committed suicide.
The inquiry will determine whether he acted deliberately or whether the equipment he was carrying caused his death, Liege prosecutor Daniele Reynders has told the Telegraph.
Authorities have told the media that Amrani had a criminal record but wasn't a man known to them for violent crime.
But who is Nordine Amrani?
Reynders has said that Amrani is a 33-year-old man who was convicted on drug and illegal arms possession charges, according to the Telegraph. He was also convicted of other crimes that included holding stolen goods.
Amrani was sentenced to 58 months in prison in September 2008 after police found several weapons in his home. He was allowed early release last year, a report noted.
According to the Telegraph, authorities found an arsenal of 10 firearms and 9,500 gun parts. Police also found 2,800 cannabis plants.
At no moment in any of the judicial proceedings against him was there a sign of a disturbance, Reynders told a news conference after the incident, as reported by the Telegraph.
The New York Times reported that a witness who was in the square told Belgium's RTL television that he saw a man throw grenades before firing an assault rifle at the crowd.
The man said that when the weapon seemed to have run out of bullets, the suspect used a revolver and he shot himself in the head.
Among those killed by Amrani are a 15-year-old, a 17-year-old, and a 75-year-old woman.
The Times report noted that Belgian media reported that a fifth victim has died after being hospitalized.