HAMBURG, Germany -- Police have struggled to gain control over street violence while world leaders dined together and attended a classical-music concert after the first day of the Group of 20 (G20) summit.
Smoke hovered in the air over the city on July 7 from fires lit by small factions of radicals among an estimated 100,000 antiglobalization protesters. They torched dozens of cars and set barricades on fire, even as German Chancellor Angela Merkel, U.S. President Donald Trump, Russian President Vladimir Putin, and the other leaders listened to the strains of Beethoven's 9th Symphony.
After a day of burning, looting, and other havoc by far-left protesters, heavily armed police commandos, using armored vehicles, water cannons, and tear gas, appeared mostly successful at clearing the streets of the downtown area by the early morning of July 8.
Still, nearly 200 of the more than 20,000 police on the streets sustained minor injuries, and police had made 19 arrests and dozens more detentions after two days of clashes in the port city. Dozens of protesters were also injured.
Merkel condemned the violence as "unacceptable."
"I have every understanding for peaceful demonstrations," Merkel said. "But violent demonstrations endanger human lives, they endanger people themselves, they put police officers and security forces in danger, put residents in danger, and so that is unacceptable."
In the night's most dramatic scenes, police pursued members of the radical anticapitalist Black Bloc movement across scaffolding as they sought refuge on rooftops while burning barricades billowed thick smoke below.
The chaos that threatened to overwhelm parts of the city during much of the day caused a few glitches in the summit -- most notably, U.S. first lady Melania Trump's motorcade was unable to leave her hotel for events she was scheduled to attend with other spouses at the summit.
But by and large, the thousands of summit participants from dozens of countries were largely unaffected by the clashes outside.
The highlight of the meetings on July 7 had been a highly anticipated first-time face-to-face encounter between Trump and Putin that extended long past its allotted 35-40 minutes, with the two leaders discussing Syria, Ukraine, and Russia’s alleged meddling in the U.S. presidential election.
U.S. and Russian officials said the meeting lasted two hours and 15 minutes and also addressed the crisis over North Korea’s illicit weapons program.
U.S. Secretary of State Rex Tillerson, who attended the meeting along with Russian Foreign Minister Sergei Lavrov, briefed reporters afterward, saying Trump pressed Putin "on more than one occasion" on Moscow’s involvement in the U.S. election.
Tillerson said the Russian leader denied any interference in the election, adding that it is "something that may be an intractable disagreement at this point."
In a separate briefing, Lavrov claimed that Trump had "accepted" Putin’s denial of meddling in the election. "President Trump said he heard clear statements from Putin that [the allegations of meddling] are not true, and that Russian authorities did not intervene, and he accepted these declarations," Lavrov said.
Tillerson, when asked while he was leaving his news briefing if this was accurate, refused to answer.
Trump did not immediately comment on the meeting, but the Russian state-run Interfax news agency quoted Putin as saying he had discussed "many issues," including "both Ukraine and Syria," along with terrorism and cybersecurity in their "lengthy conversations."
WATCH: How The Meeting Unfolded
In his briefing, Lavrov also confirmed a report by the Associated Press that said the United States and Russia had reached agreement on a cease-fire in southwest Syria, due to go into effect on July 9.
The agreement is separate from the deal on the so-called "deescalation zones" being worked out to help separate combatants in Syria’s six-year civil war.
Tillerson said the Trump administration policy sees no long-term role for Syrian President Bashar al- Assad or his family in the future government of Syria.
Video footage from before the meeting showed Putin and Trump briefly shaking hands at the G20 venue earlier in the day, with both men smiling and the U.S. president patting Putin on the back.
WATCH: Putin Calls On G20 Nations To Unite Against Terrorism
Trump has repeatedly called for improving ties with Moscow, though his administration has continued to publicly maintain pressure on Russia -- including with sanctions -- over its seizure of Ukraine’s Crimean Peninsula and backing of armed separatists in eastern Ukraine.
Trump's administration has also been dogged by the assessment of U.S. intelligence officials that the Kremlin ordered a hacking and propaganda campaign aimed at helping Trump win the 2016 U.S. presidential election -- an allegation the Kremlin denies.
Both the U.S. Congress and the FBI are investigating the alleged hacking and contacts between associates of the U.S. president and Russian officials.
In a speech in Warsaw on July 6 before meeting with Putin, Trump called on Russia to "cease its destabilizing activities in Ukraine and elsewhere" and stressed Washington's commitment to NATO, which Putin has long accused of stoking tensions in Eastern Europe.
WATCH: Protests In Hamburg Turn Violent Ahead Of G20 Summit
But Trump also downplayed the consensus among U.S. intelligence agencies, and many Republicans and Democrats in Congress, that Moscow actively meddled in the election that he ended up winning.
"Nobody really knows for sure," Trump told a news conference in Warsaw on July 6 when asked about the allegations of Russian interference.
Sitting next to Trump before the press prior to their July 7 meeting, Putin noted that while the two leaders had previously spoken by telephone, personal meetings were much more effective in dealing with "sensitive" global issues.
Trade And Climate Tensions
Meanwhile, tensions continued to simmer among G20 leaders over trade and climate change at the end of the gathering's first day.
Merkel said nearly all the leaders agreed on the need for free and fair trade, but she added that some differences are making difficult the drafting of the summit's final communique.
"On the issue of trade, virtually everyone believes we need free but also fair trade," she said. "However, I can predict that as far as trade is concerned in the communique, the [political aides] have a lot of work ahead of them tonight.”
After a July 6 meeting between Merkel and Trump, German Foreign Minister Sigmar Gabriel said "clear differences" on climate change and trade continued to divide the two allies, though they also found "many commonalities."
"The question is whether the Americans remain convinced that the only thing that counts on global trade is whether America is the winner or not," Gabriel told public broadcaster ARD.
"Or can we manage to convince the Americans that if everyone plays by the same rules, then this will be best for everyone," he said.
The G20 leaders used to routinely issue pledges to fight protectionism, but Trump's "America First" trade policy has hampered consensus among world leaders on globalization and trade since he took office.
European Commission President Jean-Claude Juncker told reporters on July 7 that the EU would respond should Washington decide to impose punitive tariffs on steel, although he did not give specifics.
The group appeared unlikely to be able to reach a consensus on climate change as well, as world leaders stepped up pressure on Trump in the wake of his withdrawal from the 2015 Paris climate agreement.
"We are not renegotiating the Paris agreement, that stays. But I want to see the U.S. looking for ways to rejoin it," British Prime Minister Theresa May told the BBC.
Merkel said that "it will be very interesting to see how we formulate the communique tomorrow and make clear that, of course, there are different opinions in this area because the United States of America regrettably...wants to withdraw from the Paris accord."
The one area of agreement leaders found was on blocking funding for extremist groups. They issued a joint statement late on July 7 underscoring their "resolve to make the international financial system entirely hostile to terrorist financing."
"There should be no 'safe spaces' for terrorist financing anywhere in the world," the leaders said.
With reporting by Rikard Jozwiak in Hamburg, AP, AFP, dpa, Reuters, and TASS