A white South Carolina police officer has been charged with murder in the shooting death of a black motorist after a traffic stop.

North Charleston Mayor Keith Summey told a hastily called news conference that city Patrolman Michael Thomas Slager was arrested and charged Tuesday after law enforcement officials saw a video of the shooting following a Saturday traffic stop.

Authorities say the victim, 50-year-old Walter Lamer Scott of Charleston, was shot after the officer already hit him with a stun gun.

Slager's attorney had released a statement Monday saying the officer felt threatened and that the motorist was trying to grab the officer's stun gun.

North Charleston Police said Slager was arrested by officers of the South Carolina Law Enforcement Division.