Police: St. Louis officers kill knife-wielding suspect in incident 4 miles from Ferguson

ST. LOUIS, Mo. -- A large crowd has gathered at the site where St. Louis police officers shot and killed a knife-wielding man after a reported convenience store robbery.

The shooting Tuesday happened just four miles from Ferguson, where a police officer's fatal shooting of an unarmed black 18-year-old, Michael Brown, has touched off days of protests.

PHOTOS: St. Louis police shooting

St. Louis Police Capt. Ed Kuntz says police responded Tuesday after a report of a robbery at the store. Police said a 23-year-old man walked out of the store with two energy drinks, where he encountered two police officers. Police said he had a knife and refused to drop the weapon.

Police Chief Sam Dotson says the man was acting erratically and told responding officers to "shoot me now, kill me now."

Kuntz says officers opened fire when the man raised the knife and moved toward them. Witnesses on the scene that spoke with ABC7 Eyewitness News dispute that he had a knife, and described the suspect as mentally disabled.

"And I heard him say 'no,' and I saw the two police officers shooting, you know, and then I saw him fall," said Doris Davies, witness.

"They gunned him down. They acted like he was charging on them and he wasn't charging them," said Chris Brown, witness.

"There were multiple shots for a man who only had a pocket knife or a butter knife or whatever he had," said Cassandra Barton, witness.

Kuntz says the suspect was black. He was pronounced dead on the scene by the St. Louis County Coroner.

The Associated Press contributed to this report.