A teenager was stabbed in the head and another injured during a skirmish.
Trouble flared between the two 18-year-olds at Downland Court in Portslade last night.
One was stabbed above the eye while the other received minor injuries.
The stabbed youth staggered to a nearby house before both were taken to the Royal Sussex County Hospital in Brighton.
The resident who raised the alarm said: "I opened the door and there was this chap covered from head to toe in blood."
Neighbours said the area had become noted for its problems.
One said: "It has never been the best place in the world to live but now it's going downhill fast."
Two people have been arrested in connection with the incident and were being interviewed at Brighton's John Street police station.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article