Police in Paris, Istanbul, Portland, Seattle New York, Seattle Washington were on high alert throughout the day as a rally in one city was marred by clashes with pro-Trump and anti-Trump marchers -- and police in another city reported Molotov cocktails being thrown at officers.
Police canceled the permit for the demonstration after "anarchists" began throwing projectiles and incendiary devices, and causing unsafe conditions for protesters, the police Twitter account said.
Incendiary devices thrown at police "included fireworks, smoke bombs and Molotov cocktails," police tweeted.
The Portland Police Bureau said in a statement that officers arrested 25 people after the march "devolved into a full-scale riot with random acts of vandalism ."
"Various fires were set in the street and in garbage cans, a police car was spray-painted and vandalized, and there were attempts to set at least one business on fire. Numerous projectiles were thrown at or launched at police and firefighters including rocks, bottles, ball bearings, fireworks, smoke bombs, and road flares," the bureau said.
Seattle Police issued a dispersal order after a May Day protest in the city's Westlake Park area, citing "increasing tensions and several fights."
According to the Seattle Police Department's Twitter feed, officers made five arrests
, the first for rock throwing, the second for unlawful possession of a weapon and the third and fourth for obstruction.
The fifth suspect was arrested for misdemeanor theft -- stealing another demonstrator's flag, the department said.
May Day protests in Olympia turned into what police called a riot.
Nine people were arrested on felony riot charges after a group in downtown Olympia began throwing rocks and smashing windows on local businesses.
They targeted news crews, restaurant patrons and used slingshots and pepper spray against officers, police said.
Olympia Police Chief Ronnie Roberts told reporters that a group of approximately 75 protesters split off from the larger, peaceful group around 6:30 p.m. local time near the downtown intersection of 4th Ave and Jefferson Street, and began to hurl projectiles at officers.
Nine officers were hit with what Roberts described as rocks or marbles. He said many of those arrested were carrying pipes and slingshots inside backpacks and that five businesses were damaged during the protests.
The mob began to split into several groups until a large number of officers arrived using flash bangs, and urged people to leave before they were arrested.
A small crowd of protesters that organized at Grand Central Station in New York marched west near Bryant Park. They carried signs with slogans, some reading, "Every species has a right to freedom" and "We're here, we're queer, we're fabulous." The group then marched Macy's Herald Square and began chanting within the department store.
In a separate protest, a dozen people were arrested outside the Park Avenue office of JPMorgan Chase & Co. for civil disobedience, said New York Police Department Sgt Lee Jones. The protest, dubbed "Corporate Backers of Hate," targets companies who have cultivated ties to President Donald Trump's administration and stand to profit off his policies, said Daniel Altschuler of Make the Road New York, which helped organize the protest.
At least four members of the group, which focuses on workers' rights, were among those arrested.
A NYPD spokesman later told CNN that a total of 32 protest-related arrest were made. Most of those arrested were charged with disorderly conduct, he said.
Video shows police firing rubber bullets and detaining protesters in Turkey's largest city as demonstrations became violent. At least 165 people have been detained during protests, according to the city's police headquarters.
There was a heavy police presence in the major squares across the city. After authorities canceled celebrations in Taksim Square, a traditional rallying point, thousands of protesters gathered in the city's Bakirkoy district. In addition to supporting workers' rights, marchers gathered to support democratic rights, human rights, freedom of expression and rule of law -- rights which are seen to be shrinking in Turkey.
Just days before a French presidential election that pits far-right leader Marine Le Pen against pro-Europe centrist Emmanuel Macron in a runoff, the traditional May Day workers' march took place in Paris alongside an anti-Le Pen protest.
Skirmishes broke out, and it didn't take long before police fired tear gas at protesters. Reports are emerging that police officers have been injured.
Brazilian tourist Joseane Duque says she and a friend witnessed a police officer hit a man, and she saw tear gas and heard a loud bang.
Artist Mehmet Ali Uysal, who participated in the demonstrations, said they were mostly peaceful, though he saw some violence, including two motorcycles that were set ablaze.
A large crowd gathered in the Cuban capital's Revolution Square, at the base of the memorial honoring writer and poet Jose Marti. A protester with a US flag briefly interrupted the day's celebration and was dragged off by government security officers.
Hundreds of thousands showed up in the Russian capital to celebrate International Workers' Day, according to state-run media. In Red Square, people waved Soviet and Russian flags, as well as banners supporting President Vladimir Putin's United Russia party. "Decent work, wages, and life" is a common theme at the gatherings.
People also took to the streets in Yakutsk, Khabarovsk, Vladivostok, Kazan, Novosibirsk and Salekhard, as well as in Siberia and the Urals and Volga regions, state-run media reported.
St. Petersburg, Russia
Demonstrators focused their ire not on any labor issue but on a January decision to return a cathedral, one of the city's most famous landmarks, to the Russian Orthodox Church, according to Radio Free Europe. Protesters say the church is gaining too much influence and want the cathedral to remain a museum.
Also, according to an Instagram user, anarchists and members of the Russian Socialist Movement marched, chanting, "Our movement is resistance."
A gathering of trade union and student organizations converged outside Georgia's parliament building with a group of women's right activists demanding better working conditions and an end to discrimination, Radio Free Europe reported.
The Union of Independent Trade Unions gathered, demanding the government provide better conditions for private-sector workers, which they said can be regarded as slaves at some workplaces, according to Radio Free Europe.