A second person has been arrested after a man was found outside a property with a serious head injury.

Emergency services including police, firefighters and ambulance crews descended on Clarence Place at around 7.30am after the man was found injured.

The victim, aged in his 30s, has been flown to King's College Hospital in London by air ambulance for treatment. The hospital has a specialist neurological unit.

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It is not yet known what type of head injury he sustained but police have described it as serious.

He remains in a serious condition.

An air ambulance spokesman said they were called to reports a man had been injured as a result of a fall.

The helicopter landed in a nearby park.

Police cordoned off one house in the road while they investigated. Officers have since left the scene.

VIDEO: Police in the road where a man was found with a serious head injury

Two men aged 37 and 58, both from Gravesend, were arrested in connection with the assault.

They have both been released pending further inquiries.

The injured man was discovered in the garden area outside a home.

An ambulance service spokesman said crews including a critical care paramedic were called, along with the air ambulance.

The man was treated at the scene before being airlifted to hospital.

Anyone with information can call officers on 01634 792209 quoting reference 03-149. Alternatively contact Kent Crimestoppers, anonymously, on 0800 555 111.