A murder investigation has been launched after a 40-year-old man was shot dead in a “senseless act of violence” during a memorial service in west London, police have said.

Police were called on Friday at 7.47pm after multiple shots were heard in East Acton. Officers attended alongside the London ambulance service. The victim was treated at the scene on the junction of Braybrook Street and Erconwald Street, however, he was pronounced dead.

The Metropolitan police said about 40 to 50 people were at the scene, including children. The man’s family have been informed and are being supported by specialist officers.

A postmortem examination is scheduled to establish the cause of death, but the victim is believed to have sustained a gunshot wound, the force added. No arrests have been made.

DCI Brian Howie, who is leading the investigation, said: “Our thoughts are with the family and friends of a man whose life was taken in a senseless act of violence. “We understand a large number of people had gathered for a memorial service and what should have been a time to come together in remembrance has instead left a family devastated.

“We believe between 40 and 50 people, including children, were present when this incident occurred. Someone knows what happened and we need them to come forward.

“If you were around Erconwald Street, Braybrook Street, the surrounding roads or Wormwood Scrubs playground between 6pm and 8pm, please think carefully about what you saw. Did you see anyone carrying or concealing weapons, people on bicycles acting suspiciously or vehicles being driven at speed?

“We also want to hear from anyone with photographs, video, dashcam, doorbell or mobile phone footage or who has seen anything relevant on social media.”