Three people have been killed by a gas leak explosion in New York, NBC New York reported.
Nearly 70 people were hurt and others are missing after two buildings collapsed following the explosion in upper Manhattan, officials said.
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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.
Police and coastguard discovered the bodies of 42-year-old Cheryl Tompsett and her five-year-old son Leo Tompsett on Monday.