A man was attacked by a gang of up to six men in Long Elms, Harrow Weald this morning.
Two men were taken by London Ambulance to a north London hospital after the assault at 5.40am but the extent of their injuries are not yet known.
Roads were closed for forensic officers to gather evidence and two men have been arrested on suspicion of grievous bodily harm.
A 44-year-old neighbour, who did not wish to be named, said she heard men fighting in the street.
A cordon has been put in place around the crime scene and Harrow CID officers are investigating.