Police launched a manhunt for an “armed and dangerous” pensioner suspected of carrying out an office shooting in Arizona that left one man dead and two wounded.

An Arizona sheriff has announced plans to deploy an armed volunteer posse to protect students in the wake of the Connecticut school shooting.

US stocks dipped, recording their first loss of the week as President Barack Obama and Republicans in Congress sniped at each other and a deadline to avoid sweeping tax increases and government spending cuts drew closer.