A man in his 20s has died and three others are being treated for "life-threatening injuries" following reports of men fighting in Essex.
Police have launched a murder investigation after officers found the man had been stabbed in the chest and died at the scene in Blackshots Lane, Grays.
Three men are being treated at Basildon Hospital for injuries believed to be life-threatening, police added.
Officers said the incident, at around 12.35am on Saturday, was believed to be linked with another in nearby Fleming Road, Chafford Hundred, where a 17-year-old was knocked unconscious at around 1.55am.
An investigation into both incidents has been launched and Essex Police is appealing for witnesses to call 101 or Crimestoppers anonymously on 0800 555 111.