Top kill

WASHINGTON - US President Barack Obama arrived in Louisiana Friday to tour what has become the worst-ever US oil disaster, as energy company BP's critical top-kill operation to cap the ruptured well in the Gulf of Mexico entered its third day.

COVINGTON, La. - BP kept pumping heavy mud into its blown-out well beneath the Gulf of Mexico on Friday, but the company's chief executive cautioned it will be two more days before anyone knows if the latest fix attempt will end the uncontrolled flow of crude that has already become the worst oil spill in U.S.