Eleven people have been arrested on suspicion of murder after a 20-year-old man died following what police described as an 'altercation' in St Albans.
Those arrested, which includes two teenage girls and two women, remain in police custody.
Police were called to the London Road just before 3.30am this morning where they found the injured boy in his late teens.
He was taken to Watford General Hospital where he died a short time later.
Shoppers this morning said there is a heavy police presence around London Road and a police forensic tent has been put up.
If you have information about this incident you should call police on 101 or, if you wish to remain anonymous, call independent charity Crimestoppers on 0800 555 111.