London police arrested a second man Sunday in connection with a suspect who drove up to a police van not far from Buckingham Palace then reached for a 4-foot (1.2-meter) sword, an incident detectives called a terrorism attempt.
Scotland Yard said three officers were slightly injured when they confronted the 26-year-old man who allegedly drove at the police van then stopped in a restricted area outside the gates of Queen Elizabeth II's London residence Friday night.
The driver reached for the sword in his car and repeatedly shouted "Allahu akbar!" ("God is great" in Arabic) during the incident, police said. The officers used tear gas to incapacitate the man and arrested him at the scene.
No one other than the man and the officers were injured. Two of the officers were treated for minor cuts in the hospital, while the third did not require hospital treatment.
Police said a second suspect, a 30-year-old man, was detained Sunday in west London on suspicion of involvement in terrorism. Officers were searching an address in the area as part of the probe.
Police had said Saturday they believed the first suspect was acting alone and were not looking for potential accomplices. The force has obtained a warrant to detain him until Sept. 1.
"This is a timely reminder that the threat from terrorism in the U.K. remains severe," Metropolitan Police counterterrorism chief Dean Haydon said. "While we cannot speculate on what the man was intending to do — this will be determined during the course of the investigation — it is only right that we investigate this as a terrorist incident at this time."
Palace officials declined to comment. British media reported that no members of the royal family were in Buckingham Palace, one of London's top attractions, at the time. The queen typically spends the month of August at her Balmoral estate in Scotland.