A man was stabbed several times and another suffered leg injuries when they were attacked by a gang.
Officers were called to the Hammersmith Palais in Shepherd's Bush Road, west London, just after midnight on Friday, where they found the two men.
The gang of about eight men are thought to have got away in a number of taxis.
Shepherd's Bush Road from the junction with Broadway to the Littlebrook Green junction is likely to stay closed for the rest of the morning.
Both of the injured men are being treated in central London hospitals.
Forensic examinations are being carried out at the scene.