Sources say police have arrested two people thought to have helped a suspect make a getaway following a knife attack on customs officers on Thursday,

It's understood that police suspect the duo of arranging transport for the 38-year-old suspect, who remains at large and is the subject of an ongoing police manhunt.

He had allegedly attacked customs officers with a knife on Thursday during a drug raid in To Kwa Wan, injuring three.

The suspect was said to have refused to cooperate during an anti-narcotics operation, before attacking the officers, who were taken to hospital for treatment.

Police have seized what appear to be firearms, along with suspected drugs from the raided flat.

Officers also found a 30cm-long knife in a stairwell.