People have been using social media to #PrayForLondon and show solidarity with the UK capital after a terror attack took place in Westminster.
Musicians, actors and sports stars from the US and elsewhere were among the many to tweet the hashtag.
Wow just heard about what's happening in the U.K. Keeping everyone affected by this terror attack in my prayers ???? #PrayForLondon
— Brennen Taylor (@BrennenTaylor) March 22, 2017
our hearts are with you london. #PrayForLondon ?
— machineheart (@machineheart) March 22, 2017
#PrayForLondon heart and soul with all the families affected today. Desperately sad, but we go on, they don't win.
— Minnie Driver (@driverminnie) March 22, 2017
Britain will never cower to terrorism. Tonight we unite & stand strong! #PrayForLondon
— Liv Cooke (@LivCookefs) March 22, 2017
— Dan Evans (@Evo151216) March 22, 2017
People have been sharing their thoughts and messages of hope alongside it.
Sending love and help to #London and all the people involved in this tragic event.
Our thoughts and prayers are with you.#PrayForLondon— Louis ITALIA (@TommosNewsIT) March 22, 2017
Hope everyone in London is alright #PrayForLondon
— Victoria matthews ?? (@_QueenVic_2011) March 22, 2017
#PrayForLondon Terrorists are terrorists. No religion to be blame. Let's pray for all the casualties& injured. Let's pray for better days??
— ??????.SMOL??? (@MYoongi_0309) March 22, 2017
A number of pedestrians were mowed down by a car on Westminster Bridge, before the attacker jumped out of the car and fatally stabbed a police officer in the grounds of the Palace of Westminster. Four people have died, including the police officer and his attacker who was shot by another officer.More than 20 people are reported to have been injured, while one woman was rescued from the Thames and treated for serious injuries after being pulled from the water.