Authorities in Missouri are braced for a weekend of reinvigorated protests around the city of Ferguson over the killing of Michael Brown, after another black 18-year-old was shot dead by a police officer in nearby St Louis.

Three days of demonstrations, marches and acts of civil disobedience have been scheduled by activists demanding justice for Brown, an unarmed 18-year-old whose shooting by a police officer led to intense unrest in Ferguson, a northern suburb of St Louis, in August.



The plans were given fresh impetus after Vonderrit Myers Jr was killed by an off-duty officer in south St Louis on Wednesday night. Police said Myers was shot after shooting at the officer three times with a handgun following a chase. The officer, who fired 17 times, was unhurt.

Myers’s death led quickly to tense scenes. Dozens of angry demonstrators chanted slogans such as “hands up, don’t shoot”, the motto of those protesting over the shooting of Brown, while relatives mourned. Police were forced to close down sections of a major thoroughfare.

Speaking at a hastily-convened press conference in the early hours of Thursday, St Louis police chief Sam Dotson said that an unidentified six-year veteran of the police department had been patrolling in the Shaw neighborhood at about 7.30pm while working a second job for a private company.

After spotting three young African American men walking, the officer reported seeing the men flee and subsequently began a car chase, said Dotson. He said that the officer left his vehicle and began pursuing on foot.

A physical struggle occurred between the officer and one of the men, identified by relatives as Myers, and the officer reported seeing a 9mm gun after the man’s hooded sweatshirt came off. Dotson said the man then fired three shots at the officer, and tried to fire additional shots but his weapon jammed. Dotson said ballistic evidence recovered at the scene supported the officer’s claims of coming under fire.

In a later statement, police said Myers’s 9mm handgun was recovered from the scene and had been reported stolen on 26 September, rebutting claims from relatives who said Myers was only holding a sandwich. Myers was charged with possession of an unlawful weapon and resisting arrest in June, and was placed under house arrest.

The mayor of St Louis, Francis Slay, said in a Facebook post on Thursday that federal authorities would examine the shooting for potential civil rights violations. Slay said that Richard Callahan, the US attorney for Missouri’s eastern district, would review all the evidence collected by investigators at the same time as Jennifer Joyce, the city’s elected circuit attorney, who will also consider criminal charges.

“If no charges are filed, the circuit attorney will release all of the investigative evidence and information so everyone knows exactly what happened,” Slay wrote.

It was unclear how the latest shooting would play out in Ferguson at the weekend.

A crowd gathers near the scene on Shaw Boulevard where a man was fatally shot. Photograph: David Carson/AP

Mervyn Marcano, a spokesman for Ferguson October, said the group expected to draw between 6,000 and 10,000 protesters for what it calls “three days of resistance”. He said the protests were aimed at “making those who are comfortable uncomfortable”, adding: “Folks want to continue the momentum.”

Ashley Yates, a co-founder of Millennial Activists United, told a rally in New York earlier this week that there would be a “mass convergence on Ferguson” this weekend. “We’re hoping for the same response we got in the first week, only with some organisation this time,” she said.

Protesters plan on Friday to march on the office of Bob McCulloch, the St Louis county prosecutor who has been presenting evidence on Brown’s death to a grand jury that is considering criminal charges against Darren Wilson, the officer who killed him.

Activists accuse McCulloch of pro-police bias. They are demanding that the prosecutor, whose father was a white police officer shot dead by a black man, step aside and that Missouri governor Jay Nixon appoint a special prosecutor for the case. Protesters are also calling for the resignations of Ferguson’s mayor, James Knowles III, and the city’s police chief, Tom Jackson.

Wilson, who is white, shot Brown six times following a dispute after Brown and a friend were stopped for walking in the middle of the road. Several witnesses say that Brown was shot while fleeing and with his hands up. Police say that he assaulted Wilson, who has been in hiding since the shooting.

Police cracked down on protests that followed Brown’s death in August with a militarised presence including armoured vehicles and dozens of armed officers in riot gear. Demonstrators were shot with teargas and rubber bullets. More than 220 people have been arrested since the protests began.

St Louis county prosecutor Bob McCulloch, whom activists have called to step away from the Brown case. Photograph: UPI/Landov/Barcroft Media

Mike O’Connell, a spokesman for the Missouri department of public safety, told the Guardian that authorities had been meeting “to get ready for this weekend’s protests.” He said that the response of law enforcement would be “appropriate and measured”.

This weekend’s planned protests also come amid tensions highlighted by the release of footage showing white fans of the St Louis Cardinals, the city’s baseball team, taunting black protesters demonstrating over Brown’s death, and endorsing Wilson, the officer who shot him.

The team’s management appealed for unity in a statement provided to the Guardian after the recording showed fans chanting: “Darren Wilson” and “Let’s Go, Darren!” One white fan wore a sign reading “I am Darren Wilson” taped to the back of his team jersey, while another was captured in a second video clip appearing to give a Nazi-style salute to demonstrators.

The plans also follow the high-profile interruption by protesters of a performance by the St Louis Symphony Orchestra. Demonstrators, who had bought tickets, broke out in song during the orchestra’s performance of Johannes Brahms’ Requiem and unfurled banners in support of Brown. Some members of the audience applauded while others objected.

Elon James White, a prominent black broadcaster, was among those who predicted the killing of Myers would intensify the weekend’s demonstrations. “Folks keep asking me do I think it’s gonna be rough in St Louis & Ferguson over the next few days,” he said on Twitter. “I kept saying ‘I don’t know.’ Now I do.”