Frustration and anger among young black Americans at an older generation’s apparent failure to adequately respond to the killing of Michael Brown by a white police officer in Ferguson upended a key event at a weekend of mass protest on Sunday.

The showdown exposed a generational divide over how best to confront police racism, brutality and use of excessive force as organisers of the “weekend of resistance”, which has drawn activists from across the US, plan to stage mass civil disobedience across St Louis on Monday.

While older civil rights leaders hark back to the more peaceful methods of half a century ago, some younger people question their effectiveness today and are pressing for more confrontational tactics.

The fuse was lit when hundreds of people who came to hear the intellectual and activist Cornel West speak were subjected to speeches by a succession of preachers from the major religions offering essentially the same message about loving one’s fellow man and standing up against injustice. The meeting was billed as being “in the tradition of the civil rights movement” but the tone was in part governed by the venue for the meeting, St Louis University, a Catholic institution.

Some in the audience grew restless and then angered at the series of reverends, imams and rabbis until a small group of activists demanded to speak. They were supported by chants of “let them be heard” and “this is what democracy looks like”, a rallying cry at protests over Brown’s shooting.

Tef Poe, a St Louis rapper and activist for Hands Up United, a campaign group seeking racial justice in Ferguson, took the microphone and noted that the Christian, Jewish and Muslim preachers on the stage were not the people on the street trying to protect people from the police.

“The people who want to break down racism from a philosophical level, y’all didn’t show up,” he said to loud cheers.

At that point, the planned programme fell apart and the focus shifted. Some younger black speakers demanded to know whether the people on the stage had a plan of action.

“All those speeches before, you’ve heard them all before. That’s not going to change, right?” said one. “I was hoping for a plan from our elders and I was disappointed,” said another.

A young man used more graphic language. “I’ve been out there since motherfucking August 9,” he told the various preachers. “If you don’t turn up at the protest get the fuck out of here.”

By then some had already left the stage, although it was not clear if it was because they were unhappy at the turn of events or to make space.

In the midst of this, a lone white man in the audience caused uproar when he shouted that African Americans should not underestimate white people’s “gift to you”. The man had to be escorted from the arena.

West did not disappoint the audience, telling listeners that an older generation of African Americans had failed them.

“The older generation has been too well adjusted to injustice to listen to the younger generation. The older generation has been too obsessed with being successful rather than being faithful to a cause that was zeroing in on the plight of the poor and working people,” he said. “Thank God the awakening is setting in. And any time the awakening sets in it gets a little messy.”

A little later he drew loud cheers as he sharpened his argument. “What our young people are also upset about is that they understand that too many of our black middle class brothers and sisters have been ‘reniggerised’. All you’ve got to do is give big positions, give them some status, give them a little money, but walking around they’re still intimidated, they don’t want to tell the truth about the situation.”

One of the earlier speakers, Reverend Traci Blackmon, touched on a similar theme.

“We have been fooled all these years into thinking that when a few get through the doors all is well. Our generation has been guilty of confusing access with ownership,” she said.

Not all the earlier speakers were unwelcome. Hedy Epstein, a 90-year-old Holocaust survivor who was part of the kindertransport to Britain, told how she arrived in the US in 1948 and was taken aback by racial segregation where she was living in the south. Epstein was arrested in August after joining a protest over Brown’s killing and is awaiting trial for “failure to disperse”.

But the meeting appeared to mark a watershed as protest organisers prepared for what is billed as a day of civil disobedience on Monday, modelled on “Moral Monday” demonstrations launched over political policies in North Carolina, by training volunteers in passive resistance and what to do if they are arrested. Churches ran a “faith in action mobilizing training” session on Sunday afternoon that included the occupation of a police station. At other sessions, volunteers were instructed in blocking traffic and sit down resistance.

Organisers of the “Weekend of Resistance” have kept their plans for Monday to themselves but say they will alert activists to actions at short notice by text message, Twitter and other social media.

At the end of the mass meeting, one of the young people who had taken over the stage called on people to join a protest vigil at the site where St Louis police last week shot another 18 year-old black man, Vonderrit Myers. The police said Myers shot at an officer who attempted to stop him for a “pedestrian check”. His family say he was unarmed.

As the protesters gathered and debated how confrontational to be with the police, Myers’s father appeared and told them: “Whatever it is y’all want to do, I’m fine with it”. Demonstrators began blocking roads in the area.

In the early hours of Sunday morning, dozens of activists attempted to occupy a convenience store in support of Myers. The police arrested 17 people for unlawful assembly.