The officer and the man tussle on the ground.
Shocking footage appears to show a police officer being punched in the head as he wrestles a suspect to the ground in East London.
Passersby could be seen posing for selfies as two officers were allegedly assaulted while trying to speak to a suspect in Hackney.
As a crowd gathered around one of the officers, a second man could be seen arriving with a baseball bat. Shortly after, footage shared online appeared to show the officer being punched in the head.
Home Secretary Priti Patel has condemned the attack, describing it as: "Sickening, shocking & disgraceful. My thoughts are with the outstanding officers who were subject to this disgusting violent attack."
Hackney's own borough commander, Marcus Barnett, said: "This is truly despicable & society should never accept such behaviour - we are here to protect you! The officers are safe, but clearly shaken & incredibly brave too. Arrests will be made... this must stop."
Two men are in custody at an East London police station tonight following the incident, with both officers suffering minor injuries. Neither required hospital treatment.
London Mayor Sadiq Khan has hit out, writing: "Attacks on our police will not be tolerated. I urge anyone with information to come forward to ensure the perpetrators of this disgusting attack feel the full force of the law. These brave officers were doing their duty and assisting the public - I wish them a speedy recovery."
Two officers were responding to an assault just after 3.30pm today after they were flagged down by a member of the public. According to Met Police, the victim pointed out their attacker and officers went to speak to those involved.
A Met Police spokesman said: "As an officer attempted to speak with those involved, one of the men resisted and a struggle ensued. A number of other people became involved whilst the officer was on the ground."
Footage shared online shows a uniformed officer with his arm around a suspect's neck.
He appears to try and throw the suspect to the ground, but instead they both end up on their backs.
As the officer calls for backup, the man he was trying to detain repeatedly shouts "Leave me the f*** alone," while holding one of the officer's wrists.
Four people, two on bikes, quickly crowd around the altercation. Two more men arrive, one carrying a baseball bat.
Seconds later, a punch appears to land on the back of the officer's head, who is still on the floor.
As one member of the crowd leans over to shout at the officer, his colleague arrives at the scene and screams at the crowd to "get back".
When she attempts to push the crowd away, they grab at her arms and begin to shout at her.
One of the crowd then dances in front of the altercation, while appearing to take a selfie.
In a separate video, members of the crowd are seen kicking at the female officer's legs as she tries to break apart her colleague from the suspect.
Chief Superintendent Roy Smith tweeted this evening: "I can confirm colleagues are aware of this horrific attack on our officers simply doing their job to protect Londoners."
Superintendent Martin Rolston, from the Central East Command Unit, said: "This incident, which was captured on someone's mobile phone is truly shocking.
"My officers went to the assistance of a member of the public – who asked for their help – after stating that they had been assaulted. What happened next is a reminder of the risks our officers take whilst going about their duties.
"It is fortunate that their injuries are not more serious. There is no place for this level of violence on our streets.
"We are engaging with our community partners to discuss what happened and I hope that anyone who witnessed what happened comes forward and speaks with us."
Shaun Bailey, the Conservative candidate for next year's London Mayoral elections, tweeted this evening: "This is appalling. Police officers attacked in Hackney today. This is what happens when you try to appease the mob. You lose control of the streets."
Mayor of Hackney Phillip Glanville told followers: "Anyone seeing these videos tonight will be as shocked & horrified as I am by this attack on two Hackney police officers. My thoughts are with both officers & praise their bravery when faced with this situation. Our police are here to protect us & scenes like this are unacceptable."
Patel told MPs that at least 35 officers had been injured during Black Lives Matter protests in London as she said she "salutes their bravery".
She said: "As the ugly tally of officer assaults shows some protesters regrettably turned to violence and abusive behaviour at the weekend.
"This hooliganism is utterly indefensible. There is no justification for it. There is no excuse for pelting flares at brave officers, throwing bikes at police horses, attempting to disrespect the Cenotaph or vandalising the statue of Winston Churchill, one of the greatest protectors of our freedoms who has ever lived.
"It is not for mobs to tear down statues and cause criminal damage in our streets and it is not acceptable for thugs to racially abuse black police officers for doing their jobs.
"The criminals responsible for these unlawful and reckless acts are betraying the very cause that they purport to serve."