LONDON (CBS4) – London is recovering after a terror attack on its subway system, and Denver Mayor Michael Hancock is there right now.

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The mayor tweeted Friday morning that he and the Denver city delegation he is traveling with is safe.

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Hancock said in part: “Please pray for affected individuals and their families.”

An explosion happened at the Parson’s Green London Underground train station and reportedly injured at least 22 people. No one was killed.

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The Denver team officially opened the London Stock Exchange on Friday.