So far, only [1] Sky News has this. Assiduous searches elsewhere turned up only a BREAKING NEWS alert about actor Tony Randall's death.

More details when available.

UPDATE: According to AFP, none of the four included Abu Mussab al-Zarqawi, who US authorities believe carried out the killing.

Four people have been arrested over the beheading of American Nicholas Berg, Iraq sources say.

The 26-year-old businessman's decapitated body was found 10 days ago in Baghdad.

UPDATE: [2] AFP has more.