A man fired bullets and hurled grenades into a crowd of Christmas shoppers Tuesday, killing 5 and injuring 132 in eastern Belgium.

Authorities named Nordine Armani, 33, as the attacker, who also died in the violence. The man had a history of drug and weapons offenses, according to the Los Angeles Times. Officials say they do not know what prompted Armani to open fire on a crowded square in Liege.

The attack began shortly before noon in Place St. Lambert, a square which is home to the city's cathedral, courthouse and a busy Christmas market. 

"I heard a loud boom," witness Dimitri Degryse told the Associated Press. "I thought it was something on my car that was broken or something. Then a few seconds after, a second boom, and I saw all the glass breaking. I saw people running, screaming."

Officials have ruled out terrorism or a known mental disorder as the reason for the attack but have yet to determine why he acted, the BBC said. 

Armani, who was on parole, was asked to come to the police station to answer questions related to charges against him. Instead, he went to the busy square and threw three grenades at people waiting for buses. Armani then opened fire, sending the crowd fleeing, BusinessWeek reported. 

15 and 17-year-old schoolboys ,who were leaving exams, were among those killed. So was a 75-year-old woman. A 17-month-old girl joined the list of victims when she died at a hospital, despite hours of emergency care. She was the fifth fatality.

"I am perplexed, I am horrified,” said Van Rompuy, the former Belgian prime minister from December 2008 to November 2009.

Armani's criminal record is extensive, with over 20 brush-ins with law enforcement. According to Expatica Belgium:

 A Belgian judicial source confirmed that Amrani's history and the scale of his run-ins with justice was well known to the police and magistrates.

RTL reported that in 2007, Liege police discovered rocket-launchers, an AK-47 rifle and pump-action shotguns among a cache of arms running to 9,500 pieces, for which he landed a near five-year jail term the following year.

Belgian officials told AFP he had been released on parole in October 2010, a spokesman for Belgium's prisons service saying he was not aware of any cross-surveillance with a Belgian national centre for threat evaluation, OCAM.

Officials are investigating the motives behind the public massacre.