WINSTON-SALEM, North Carolina (REUTERS) - A man armed with a shotgun and a bag of ammunition opened fire outside a law firm and a Walmart store in Greenville, North Carolina, on Friday, shooting four people before police shot him, the city's police chief said.

The suspect and the victims underwent surgery for gunshot wounds and were expected to survive, Greenville Police chief Hassan Aden said.

One person was shot while sitting in his car outside a law firm, and three others were struck after the suspect walked across the street and fired his gun in the Walmart parking lot, Mr Aden said.

The suspect then fired one round at officers who had responded to the scene, Mr Aden said, adding that as police chased him, he levelled his gun and was shot "multiple times" by police.

The gunman, who was taken into custody but not identified, was carrying numerous rounds of ammunition, said the chief, who added that the swift response by police "ended this quickly before he was able to shoot anybody else".

No charges had been filed as of Friday evening, and no motive had been determined.

"It just looks like it was very deliberate and planned," Mr Aden said.

A spokesman for Walmart said no one was shot inside the store and all associates were safe after what appeared to be a random shooting involving several businesses.