Rory McIlroy said he felt "absolutely incredible" after wining the British Open but that his success "still hadn't sunk in yet."
The 25-year-old told a press conference he would be celebrating tonight with his friends and family. "I'll get to enjoy it and let it sink in tonight," he said.
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The incident is not believed to be terror-related, British Transport Police said.
The royal couple have been in the US to mark the 300th anniversary of the foundings of New Orleans and San Antonio.
A small number of people were treated at Southgate Tube station, British Transport Police said.