Three men have been arrested on suspicion of murder after a 24-year-old died after being stabbed.
Officers were called to reports of men fighting in Blackshots Lane, Grays, in the early hours of Saturday and discovered a man had been stabbed in the chest.
He died at the scene, while three other men aged 18 to 39 suffered "life-threatening injuries" including a chest wound and serious stomach wound, Essex Police said.
The arrested men, aged 18, 21 and 22, remain in custody.
Detective Inspector Stuart Truss of the Kent and Essex Serious Crime Directorate said: "Although we have made arrests, our inquiries are ongoing.
"A number of witnesses have already come forward and I am grateful for their assistance.
"We have been told there were a number of people in the area at the time and I want to speak to anyone who was in Blackshots Lane who saw what happened and can help us piece together the events leading up to this incident."
Witnesses are asked to call 101 or Crimestoppers anonymously on 0800 555 111.