BRUSSELS (AP) -- At least two American citizens have been confirmed killed in this week's attacks in Brussels, a U.S. official says, as Secretary of State John Kerry is visiting the city to express his condolences to the Belgian people.

   Speaking after meeting with Belgian Prime Minister Charles Michel, Kerry said the "United States is praying and grieving with you for the loved ones of those cruelly taken from us, including Americans, and for the many who were injured in these despicable attacks."

   He did not give a specific number but a senior official said the families of two Americans had been informed of their deaths in Tuesday's attacks. The official, who was not authorized to speak to the matter publicly and spoke on condition of anonymity, did not have further details.