Ten people were being questioned on suspicion of murder today after a young man died during a New Year's Eve party, police said.
The body of the 23-year-old, who was named locally as Kevin Rogers, was found in the street outside the house party in Leyland, Lancashire, at 5.30am yesterday.
Seven men, aged between 17 and 42, and three women, aged 23, 33 and 39, were arrested on suspicion of murder, and two other men were arrested on suspicion of assault and criminal damage, Lancashire Police said.
Mr Rogers did not live at the address in Edgehill Crescent but was a guest at the party and lived locally, neighbours said.
It is thought he suffered a blow to the head, and was later pronounced dead outside the house where the party was held.
Officers yesterday searched through the bins of the semi-detached property, which has a smashed front window.
One neighbour, who did not wish to be named, said he was "a lovely boy".
"I did not know him very well but he was always friendly," she said.
Another neighbour said she woke up to find the street swarming with detectives, uniformed officers and forensics teams.
"It is not something you expect to wake up to, especially on New Year's Day, it's awful," she said.
Det Supt Andy Webster, who is leading the investigation, said the community should be reassured that the incident was "extremely rare".
"We have put all of our resources into this investigation.
"Despite it being New Year's Day, we have got around 50 police officers and 20 detectives working on it.
"I want the community to know we are doing everything we can, and would still urge anyone who might know anything to come forward."
Earlier, he said: "Although it was very early in the morning, it may well be that people were returning home after the New Year celebrations.
"Any amount of information, no matter how small, could be crucial to this investigation."
The area has been sealed off while crime scene investigators carry out their work and an incident room has been set up at Chorley police station.
A post-mortem examination will be carried out to establish the cause of the man's death.
Neighbourhood policing teams are working with the local community and extra patrols are being stepped up in the area, he added.