LIEGE, Belgium  — Summoned for questioning by Belgian police, a man with a history of weapons and drug offenses left home armed with hand grenades, a revolver and an assault rifle. Stopping at a central square filled with holiday shoppers, he lobbed three grenades into the crowd, then opened fire.

Four people were killed, including an 18-month-old toddler, and 122 were wounded in the assault Tuesday that brought tragedy to the pre-Christmas season of students reveling in exam results and preschoolers enchanted by brightly lit trees and holiday stalls.

Authorities said the shooter also died, but they were at a loss to explain the reason for the onslaught. The prime minister said it was not related to terrorism.

In a second burst of deadly violence in Western Europe on Tuesday — attacks rare for the continent — a man shot and killed two Senegalese vendors at a market in Italy.

The midday attack in the eastern Belgian city of Liege sent hundreds of panicked shoppers stampeding down the cobbled streets of the old city, fleeing explosions and bullets.

Belgian authorities identified the shooter as Nordine Amrani, a 33-year-old Liege resident who had done jail time for offenses involving guns and drugs, and had been called in for questioning Tuesday in a sexual abuse case.

Officials said Amrani left his home with a backpack, armed with hand grenades, a revolver and an FAL assault rifle. He walked alone to the busy Place Saint-Lambert, the central entry point to downtown shopping streets, then climbed onto an overpass that gave him an ideal view of the square, which was bedecked with a huge Christmas tree and crowded with shoppers.

From there, Amrani lobbed three hand grenades toward a central bus stop, which serves 1,800 buses a day, and opened fire. The explosions sent shards of glass from the bus shelter across a wide area.

"I heard a loud boom," said Dimitri Degryse, who was driving near the square. "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."

Hundreds fled the square as well as a nearby Christmas market. Video showed people, including a large group of preschoolers, rushing to seek cover, some still carrying shopping bags.

Amrani died at the scene, but Liege Prosecutor Danielle Reynders told reporters he was not killed by police. It was unclear if he committed suicide or died by accident, though he still had a number of grenades with him.

Those killed were two boys ages 15 and 17, a 75-year-old woman, and an 18-month-old toddler who died Tuesday evening in the hospital, Liege police said.

As police hunted for possible accomplices, residents were ordered to stay in their homes or seek shelter in shops or public buildings. Sirens blared and a police chopper roared overhead, and a medical post was set up in the nearby courtyard of the Prince Bishops courthouse. Dozens of emergency vehicles took victims away for treatment.

Police closed off the area but found no accomplices, and calm returned a few hours later.

The Place Saint-Lambert and the nearby Place du Marche host Liege's annual Christmas market, which features 200 shops and attracts some 1.5 million visitors a year. A nearby Ferris wheel is also a central attraction.

By dusk, with the Christmas lights gleaming again, King Albert II and Queen Paola came to pay their respects, as did Prime Minister Elio Di Rupo.

Di Rupo stressed the attack was the act of a lone assailant, a man known to police who had no links to terrorism. "The whole country shares in the pain. This is an isolated case. This is not about terrorism," he said.

Herman Van Rompuy, a former Belgian prime minister who is now president of the European Council, said he was badly shaken by the attack.

"There is no explanation whatsoever," Van Rompuy said. "It leaves me perplexed and shocked."

While such attacks are unusual in Western Europe, the continent has not been immune to such violence.

There was another deadly shooting Tuesday in Italy, where a man opened fire in an outdoor market in Florence, killing two vendors from Senegal and wounding three other Senegalese before killing himself, authorities said.

Investigators identified the attacker as 50-year-old Gianluca Casseri, and RAI state TV said he was known to police for having participated in racist marches by an extreme right-wing group.

In Norway last July, far-right extremist Anders Behring Breivik went on a bomb and shooting spree that killed 77 people in Oslo and an island retreat, apparently motivated by a hatred of Muslim immigrants and a deep grudge against the governing Labor Party. A psychiatric evaluation found him criminally insane, which if upheld by the courts means he would end up in compulsory psychiatric care instead of prison.

Rescuers evacuate injured people at the Place Saint Lambert square where two men threw explosives in the city center of the Belgian city of Liege Dec 13, 2011. [Photo/Agencies]