Police patrolled the streets of London as tens of thousands of protesters descended on the U.K. capital on Saturday for two rival demonstrations, and tens of thousands more soccer fans congregated for the final of England’s major domestic cup competition at Wembley Stadium.

Armored vehicles, police horses, dogs, drones and helicopters were deployed along with at least 4,000 officers as the Metropolitan Police aims to avoid clashes. Hundreds more are on standby.

Police tried to make sure there was no crossover between the march organized by far-right agitator Stephen Yaxley-Lennon, better known by his pseudonym Tommy Robinson, and the annual demonstration to commemorate Nakba, the Arabic term for “catastrophe” that marks the exodus of some 700,000 Palestinians from what is now Israel in 1948.

So far, there’s not been much trouble

As of mid afternoon, police said 31 people had been arrested for a variety of offenses.

“While this may seem high, to this point both protests have proceeded largely without significant incident,” the Met said.

The marches took place at a particularly radicalized time in British politics, with the extremes on the right and the left advancing across the U.K. in elections last week.

Those protesting are motivated by a variety of issues, including anger at the number of would-be asylum-seekers making the dangerous crossing across the English Channel from the French coast to the U.K. in small boats, to Israel’s actions in Gaza that have devastated the Palestinian enclave and killed, according to the Gaza Health Ministry, more than 72,700 people,

As the marches progressed through the afternoon, police said they will be mindful of splinter groups coming in contact.

Some foreigners were barred from entering UK

Prosecutors have been told to consider whether protest placards, banners and chants viewed on social media may amount to offenses of stirring up hatred during the rallies.

“This is not about restricting free speech,” said the Crown Prosecution Service’s director, Stephen Parkinson. “It is about preventing hate crime and protecting the public, particularly at a time of heightened tensions.”

The British government has also blocked 11 foreign nationals from entering the country for the “Unite the Kingdom” rally. Right-wing figures claiming to have been barred include Polish politician Dominik Tarczynski, Belgian politician Filip Dewinter, anti-Islam commentator Valentina Gomez and Dutch activist Eva Vlaardingerbroek.

“We will block those coming into the U.K. who seek to incite hatred and violence,” said Prime Minister Keir Starmer, who is fighting for his political life following those disastrous election results earlier this month. “For anyone who sets out to wreak havoc on our streets, to intimidate or threaten anyone, you can expect to face the full force of the law.”

On Friday, Starmer visited the Met’s command center to discuss policing arrangements for the rallies alongside Met Commissioner Mark Rowley and London Mayor Sadiq Khan.

Live facial recognition will be used for the first time in a protest policing operation, with cameras set up in the north London neighborhood of Camden that is not on the route of the “Unite the Kingdom” march, but which is expected to be used by a lot of people attending the event.

Farther north in the capital at Wembley, police will be hoping that the FA Cup Final between Chelsea and Manchester City, which kicks off at 3 p.m., passes off without incident. Around 90,000 fans are expected to attend.