A former University of California graduate student killed his estranged wife in Minnesota before carrying two semi-automatic pistols and a grudge back to Los Angeles, where he gunned down a young professor he once called a mentor before killing himself.

Medtronic plans to pick up a $25m tax bill for chief executive Omar Ishrak, the cost of a special penalty imposed by Congress on executives who shift their company’s tax domiciles out of the US.

At least seven people died when a freeway bridge suddenly broke into huge sections and collapsed into the Mississippi River in the US during rush-hour traffic jams.