US President Donald Trump on Monday urged state governors to crack down on protests over the death of a black man in police custody that have engulfed the nation's major cities, as local officials extended curfews that have so far failed to stop looting and vandalism.

The demonstrations, largely peaceful during the day but turning violent after dark, have erupted over the death of George Floyd, a 46-year-old African American who died in Minneapolis police custody after being pinned beneath a white officer's knee for nearly nine minutes...