New Delhi : India, the US, France, the European Union on Wednesday strongly condemned the deadly attack in London that killed at least four and injured 20 people.

"India strongly condemns Westminster terrorist incident and condoles the loss of life. No place in democracies and civilised societies for terrorism," Indian External Affairs Ministry spokesperson Gopal Baglay tweeted.

The White House said President Donald Trump spoke with British Prime Minister Theresa May and condemned the attack and applauded the quick response of British police and first responders.

French President Francois Hollande expressed solidarity with British authorities and said: "We express our solidarity and support to the British people and the Prime Minister, Theresa May..."

"We have to understand that terrorism concerns all of us, and France, which has been struck many times, can know what the British people are suffering today," he added.

Hollande also called for a European plan to set "all the conditions to respond to these attacks".

European Council President Donald Tusk offered sympathy to Britain: "My thoughts are with the victims of the Westminster attack. Europe stands firm with the UK against terror and ready to help," .

European Commission President Jean-Claude Juncker said in a statement "Today marks one year since the people of Brussels and Belgium suffered a similar pain and felt the support of your sympathy and solidarity. At this emotional time, we at the European Commission can only send that sympathy back twofold."

"The United Kingdom will always remain a partner and a friend and one we will continue to work hand in hand with in the fight against terror," Juncker said.

"Together, Europeans will never cease to prove that love will always triumph over hate and that tolerance will always triumph over fear," he added.

In a statement released by the US State Department, US Secretary of State Rex Tillerson also condemned the "horrific acts of violence".

In an attack, described as a "terrorist" assault, a car was driven over Westminster Bridge, hitting and injuring a number of people and three police officers.

London police say the car then crashed near the Parliament and at least one man, armed with a knife, continued the attack, trying to enter the Parliament before being shot dead.

Four people have been killed, including the male attacker, and at least 20 injured in the attack.