Children as young as three who witnessed a young man dying after he was stabbed at a youth centre in south London have had no support or counselling, a mother has claimed.

The children were at the Marcus Lipton youth centre in Brixton, where a football training session was being held on 21 February, when Glendon Spence, 23, from Lewisham, was chased in to the centre and stabbed. He died at the scene.

Two 17-year-olds have since been charged with murder.

Spence died yards from where the Lambeth Tigers were holding a training session for five- to eight-year-olds, watched by parents and siblings as young as three.

One mother, Sarah, who asked for her surname to be withheld, told the BBC that they had responded to the fracas by lining their children up against a far wall, before she went to try to help Spence.

She said her own son, aged eight, did not see Spence, but that some of the other children did “and explained to the children what was going on”.

“And that’s left a stain in his head at the moment,” she said. “It came out days later that my son told his cousins what he had been told, and [he] had some shaking episodes.”

Sarah said that police had not been in touch – despite she and fellow parents giving their names and addresses to several officers – and that their first meeting with child and adolescent mental health services had only come on Friday, more than a week after the incident had taken place.

“We’ve pretty much been left in the dark. We have had no support, we’ve been Googling to find out information,” she said.

“We’re pretty much living victims. We’re living through this, trying to process what we have seen, as well as trying to make sure [of] the wellbeing of our children.”

Cllr Jack Hopkins, the leader of Lambeth council, said: “Last week’s senseless death of a young man in our community shocked and saddened us all here in Lambeth. It is shocking that the attack took place at one of the borough’s youth centres, which should be a safe haven for those attending.

“It is also extremely distressing that this violence was witnessed by young people, alongside the hard-working youth workers at the Marcus Lipton centre, leaving many of them traumatised.

“Lambeth council, our member of parliament Helen Hayes and the police are working together to support our community in the wake of this incident.

“Counselling has been made available for those who were affected by this incident. A public meeting is being organised so local people can highlight the local issues they think need tackling most urgently and share their insights into what needs to be done to end the violence.

“We have also set up a meeting for Lambeth Tigers who were present at the time of the attack, with myself, our officers, our MP and the deputy mayor of London for policing and crime, to discuss how we can support them moving forward.”