London bridge
People flee as police attend to an incident near London Bridge in London, June 4, 2017. Reuters

Two weeks after 22 people were killed when a suicide bomber targeted an Ariana Grande concert in Manchester, United Kingdom, attackers drove a van at high speed into pedestrians on London Bridge in the U.K. capital Saturday night. Soon after, they started attacking people on the street and those returning home from bars in the nearby Borough Market area.

Authorities described the incident as a terrorist attack, which took place less than a week ahead of the June 8 general election. Six people were killed in the attack, according to authorities cited by Reuters. While reports said over 30 people were injured, a statement by London Ambulance Service said at least 20 people had been hospitalized.

Three attackers were shot dead by police, who believe there were no more of them, the Telegraph reported, citing police officials.

Read: Student Pilot Detained By British Police In Manchester Bombing

President Donald Trump used the occasion to send a reminder about the importance of enforcement of his executive order to restrict the travel of Muslims to the United States. Minutes later, he also offered help to London and the U.K.

A statement by the Department of State said: "The United States condemns the cowardly attacks targeting innocent civilians in London this evening. We understand U.K. police are currently treating these as terrorist incidents. The United States stands ready to provide any assistance authorities in the United Kingdom may request. Our hearts are with the families and loved ones of the victims. We wish a full and quick recovery to those injured in the attacks. All Americans stand in solidarity with the people of the United Kingdom."

The office of British Prime Minister Theresa May announced she will chair a meeting of the government emergency response committee, known as Cobra, on Sunday, reports said. "Following updates from police and security officials, I can confirm that the terrible incident in London is being treated as a potential act of terrorism," May said.

The newly elected French President Emmanuel Macron tweeted: "In the wake of this new tragedy, France more than ever stands side by side with the United Kingdom... My thoughts are with the victims and their loved ones."

The Canadian Prime Minister Justin Trudeau tweeted in English and French about the “awful news from London” and to direct Canadians in need of support to official channels.

The Australian Prime Minister Malcolm Turnbull, said his country’s “prayers and resolute solidarity” were with the people of Britain. Australia's Foreign Minister Julie Bishop said her country stood ready to support the British government in responding to the attacks.

The president of the EU Commission, Jean-Claude Juncker said his thoughts and prayers were with the victims and their families.

The Mayor of Paris, Anne Hidalgo, tweeted: "The Parisians are alongside the Londoners. Our thoughts go to the victims and their loved ones."

Mexican President Enrique Peña Nieto tweeted: "Mexico condemns the Act of violence occurred in London. Our solidarity with the families of the victims and the wounded."

Indian Prime Minister Narendra Modi also took to Twitter on Sunday morning to condemn the London attacks.