About 150 people have attended fresh demonstrations and a candlelight vigil for an African-American teenager who was shot by white police officers on Wednesday in St. Louis, Missouri.

The protest and vigil was held Thursday night for 18-year-old Mansur Ball-Bey, whose death sparked angry protests on Wednesday, recalling the racial tensions fueled by the killing of Michael Brown in nearby Ferguson a year ago.

Within an hour of Ball-Bey's death, more than 100 people gathered on the streets of St. Louis, just days after the first anniversary of the fatal shooting of Brown by former Ferguson police officer Darren Wilson.

Brown's death sparked months of violent protests across the United States and spurred a nationwide movement to confront police violence against minorities.

St. Louis Police Chief Sam Dotson said Ball-Bey’s fatal shooting took place as police were conducting a search warrant and two young African-American men ran out the back door of the targeted home.

Officers ordered the two men to stop in the alley behind the house. One suspect pointed a gun at officers who then fired four times, killing him, Dotson said.

The police obtained the search warrant because they believed the house contained several suspects.

Some activists and residents are skeptical about the police chief's account that the suspect pointed a gun at police before being killed.

An autopsy shows that Ball-Bey died from a wound in the back, the St. Louis Post-Dispatch reported Friday, citing St. Louis police chief Sam Dotson.

A report released earlier this month has indicated that US police officers killed 118 people last month across the country, making July the deadliest month of this year so far.