BERLIN _ Gunfire erupted at a busy shopping mall in Munich on Friday evening, killing at least 10 people and injuring others in what police were calling a suspected terrorist attack.
Police sealed off parts of the city, Germany's third-largest, and pleaded with its 1.4 million residents to remain indoors as they attempted to determine who was responsible for the attack.
The transit system was shut down, sirens wailed and helicopters clattered overhead as local authorities declared a state of emergency.
Later, police issued a cautious all-clear, saying the attack appeared to be the work of a lone gunman who had killed himself.
It was the latest in a series of incidents of mass violence in Europe, and the second in Germany this week.
The attack in Munich started shortly before 6 p.m. Friday at a McDonald's restaurant across from the Olympia shopping center, police said.
A witness told CNN that her young son saw a man loading a gun in a restroom inside the fast-food outlet before he started shooting at diners.
"He was killing the children," said the woman, who was not identified. There was blood everywhere, she said.
Another woman described the chaos inside the restaurant.
"We'd just sat down and started eating," she told Germany's Bayerische Rundfunk TV. "The workers bolted out; the children started crying and ran around in panic."
The gunman ran into the street, witnesses said.
A video shared on social media showed a man dressed in black shooting at people outside the restaurant.
Another video showed a gunman firing from the roof of a nearby parking structure.
There were also reports of shooting inside the mall.
At least 10 people were killed, including the gunman, police said.
In the initial confusion, there were reports of shootings at other locations in the city, but police said they appeared to be false alarms.
In Washington, President Barack Obama said the U.S. was ready to offer any assistance needed to investigate the attack.
"Germany is one of our closest allies," he told reporters.
The incident was sure to provide fresh ammunition for Republican presidential nominee Donald Trump's claims that the world is facing a substantially greater risk of terrorism demanding an aggressive response.
Hillary Clinton, the presumptive Democratic nominee, said in a tweet: "We stand with our friends in Germany as they work to bring those responsible to justice."
Residents described a ghostly silence in the normally bustling city center on Friday night, a time when pubs and restaurants are usually filled with people ringing in the start of the weekend.
There was no immediate claim of responsibility, and while authorities said they were investigating it as a terrorist attack, analysts pointed out that the bloodshed could have been an act of domestic terrorism motivated by anti-immigrant sentiment.
Germany has been a key destination for hundreds of thousands of migrants from the Middle East, Afghanistan and Africa, and Merkel's government has faced a strong backlash against efforts to offer asylum for large numbers of Syrian refugees in Germany.
The latest wave of Islamist violence across Europe has added fuel to the controversy.
On Monday, a 17-year-old Afghan man attacked passengers on a train with an ax and a knife near the German city of Wuerzburg before being shot and killed by police. No one died in that attack, though one passenger remains in critical condition.
The extremist group Islamic State group claimed responsibility, releasing a video in which the purported assailant describes himself as "a soldier of the caliphate." But authorities have said the teen likely acted alone.
On July 14, 84 people were killed and more than 300 others injured when a 19-ton cargo truck was driven into a crowd along the waterfront in the southern France resort town of Nice.
Islamic State said one of its "soldiers" carried out that attack. The driver, Mohamed Lahouaiej Bouhlel, was killed by police at the scene.
"We aren't ruling out any possibilities," Chancellor Angela Merkel's chief of staff, Peter Altmaier, said of the investigation in an interview with the German public broadcaster ARD. "There's no clarity so far. I'd urge us all to wait for the investigation."
"It was a despicable attack," he said.
In the video showing a gunman on the roof of the parking garage, the assailant can be heard saying in flawless German: "I'm a German, just like you."
"You're a jerk," a voice is heard shouting at the gunman.
"I'm fed up with it all," the gunman replies.
That led ARD terrorism analyst Georg Mascolo to suggest it was possible that the attack was the work of a right-wing extremist. The shootings occurred on the fourth anniversary of the July 22, 2011, attack in Norway by Anders Behring Brevik, which killed 77 people.
Brevik on the day of the attacks distributed a series of texts titled "2083: A European Declaration of Independence," which among other things expressed opposition to Islam.
Mascolo told German TV, "The video shows one of the assailants and there are indications, because of the way he is speaking, there that there could be a remarkable turn of events tonight" in terms of shedding light on a possible motivation for the killing.
The mall is located near Munich's Olympic Stadium. The Olympic village was the scene of a terrorist attack during the Olympics in 1972, when the Palestinian militant group Black September took 11 Israeli athletes hostage and eventually killed them.
