Munich, Germany: Police were probing Saturday the motives of the lone teenage German-Iranian gunman who went on a deadly rampage at a busy Munich shopping centre, the third bloody attack on civilians in Europe in just over a week.

Nine people were killed and another 16 wounded as the black-clad gunman brought terror to Germany's third largest city on Friday evening, before committing suicide.

"Bloodbath in Munich," was the headline on the best-selling Bild newspaper as shockwaves reverberated across the continent.

The killing spree sent the southern city into lockdown as elite police launched a massive operation to track down what had initially been thought to be up to three assailants.

Chancellor Angela Merkel is to convene her security council on Saturday to address the shooting, which came just days after an axe rampage on a train in the same German state of Bavaria and just over a week after a truck attack in the French Riviera city of Nice that killed 84 people.

Grieving Munich residents laid roses and lit candles in memory of the victims, with one placard bearing the simple plea: "Why?"

Police chief Hubertus Andrae told reporters that the assailant was an 18-year-old dual national German-Iranian from Munich, who had no criminal record.

"The motive or explanation for this crime is completely unclear," he said.

Armed with a handgun, the attacker opened fire at a McDonald's restaurant and continued along the street before entering the mall.

A police patrol shot and wounded the gunman but he managed to escape, before police found the body of what they believed was the "only shooter."

Among the nine killed were three Kosovans, according to the foreign ministry in Pristina, while Munich police said the injured included children.

- Scenes of panic -

A video posted on social media appeared to show a man in black walking away from a McDonald's while firing repeatedly on people as they fled screaming.

Survivors described terrifying scenes as shoppers rushed from the area, some carrying children in their arms.

"We entered McDonald's to eat... then there was panic, and people ran out," one woman told Bavarian television.

Another video appeared to show the gunman on a car park roof exchanging a tirade of insults with a man on a nearby balcony.

"I'm German, I was born here," the assailant replies after the man fired off a volley of swear words, including an offensive term for foreigners.

Police initially believed there could be up to three assailants.

But Andrae later said two others had "absolutely nothing to do" with the attack -- and that they were simply fleeing the scene.

Munich's main train station was evacuated and metro and bus transport suspended for several hours while residents were ordered to stay inside, leaving the streets largely deserted.

By early Saturday, transport services were running again.

- 'Europe stands united' -

President Joachim Gauck said he was horrified by the "murderous attack", while US President Barack Obama voiced staunch support for Washington's close ally.

"Our thoughts are with the victims, their families, and all German people. Europe stands united," EU foreign policy chief Federica Mogherini said on Twitter.

The attack came just days after a 17-year-old asylum seeker went on a rampage with an axe and a knife on a train on Monday near Wuerzburg, also in Bavaria, injuring five people.

Interior Minister Thomas de Maiziere had said that assailant was believed to be a "lone wolf" who appeared to have been "inspired" by Islamic State group but was not a member of the jihadist network.

The train attack triggered calls by some politicians to impose an upper limit on the number of refugees coming into Germany, which accepted a record 1.1 million migrants and refugees last year, many through Bavaria.

- 'No security anywhere' -

The Munich mall is near the stadium for the 1972 Olympics and the athletes' village which was the site of the hostage-taking of Israeli athletes by the Palestinian Black September group that ended in a massacre.

Europe has been on high alert for terrorism after a string of attacks in neighbouring France and Belgium claimed by IS.

"It has reached us. People in Munich have long had a queasy feeling. Fears grew with every attack in Paris, Istanbul or Brussels," said the Abendzeitung newspaper's editor-in-chief Michael Schilling.

"There were particular concerns about the Oktoberfest. But since Friday it is clear that there can be no security anywhere, not even in the safest German city."

The mall shooting occurred just eight days after 31-year-old Mohamed Lahouaiej Bouhlel used a truck to mow down 84 people, including children, after a Bastille Day fireworks display in Nice, the third major attack on French soil in the past 18 months.

In March, IS claimed suicide bombings at Brussels airport and a city metro station that left 32 people dead.

In May, a mentally unstable 27-year-old man carried out a knife attack on a regional train in Bavaria, killing one person and injuring three others.

AFP