"Officers attended the location. The majority of those present had dispersed prior to the arrival of police," a Metropolitan Police spokesperson said as quoted by media on Sunday, adding that an "investigation was launched, and one male was arrested nearby a short time later on suspicion of violent disorder."
According to the police, windows were broken at the Indian mission. An investigation is underway and inquiries continue.
"Two members of security staff sustained injuries. These are believed to be minor; they did not require hospital treatment," the police spokesperson said.
London Mayor Sadiq Khan said on Twitter that he condemned the violence and vandalism at the Indian high commission.
The Indian Foreign Ministry has expressed protest to British deputy high commissioner Christina Scott over the pulling down of the flag outside the Indian high commission. Scott was summoned to the foreign ministry on Sunday night and the ministry demanded an explanation as to why the British security allowed the activists to enter the mission premises.
On Sunday, videos emerged on social media showing a group of supporters of the Khalistan separatist movement protesting outside the Indian mission in London. One of the protesters pulled down the Indian flag from the first-floor balcony of the building.