London, England, Mar 22, 2017 / 01:30 pm (CNA/EWTN News).- Church and government leaders offered prayers in the aftermath of an attack in London on Wednesday afternoon. “Our thoughts and prayers are with all those affected by the incident in Westminster this afternoon,” read a post on Twitter from the news page of the Catholic Bishops' Conference of England and Wales.

Details surrounding the March 22 attack in Westminster remained unclear some four hours after an attacker in a car apparently plowed into pedestrians on Westminster Bridge. The assailant then reportedly crashed the car and attempted to enter the Parliament building with a knife before being shot by armed police.   

According to the Guardian, four people were killed, including one police officer and one man believed to be the assailant. About 20 others were reported injured, some severely. Nearby government buildings were placed on lockdown while authorities worked to ensure the safety of the area. Scotland Yard said the attack is being treated “as a terrorist incident until we know otherwise.”

March 22 marks the one-year anniversary of the Brussels airport bombings that left more than 30 dead and 300 injured. Those bombings were declared the deadliest act of terrorism in Belgium's history.

While details surrounding the London attack remain uncertain, religious and national leaders offered condolences and prayers. “Please join me in praying for the people of #London, especially those killed and injured today. St. George and St. Paul, pray for us,” said Bishop James Conley of Lincoln on Twitter.

“Terrible scene in London,” said U.S. House Speaker Paul Ryan in a post on Twitter. “Praying for the victims of this apparent act of terror. We stand with our friends in Parliament and Great Britain.”

Secretary of State Rex Tillerson also released a statement offering prayers. “On behalf of the United States, I express my condolences to the victims and their families,” he said. “The American people send their thoughts and prayers to the people of the United Kingdom. We condemn these horrific acts of violence, and whether they were carried out by troubled individuals or by terrorists, the victims know no difference.”