At least 30 firefighters are tackling a huge blaze at a series of derelict warehouses in Whetstone.
London Fire Brigade was called at 9.27pm to an empty industrial park behind Allum Way, where several of the buildings, measuring 60 metres by 40 metres, were on fire.
A spokesman for London Ambulance Service said its hazardous area response team was on standby, but that no casualties had been reported so far.
Metropolitan Police officers closed Totteridge Lane for almost an hour after the incident was reported, though the road was reopened shortly before 10.30pm.
Witnesses reported seeing 40ft flames, and traffic in the area built up as cars slowed down to take a look.
Dozens of people gathered in neighbouring streets to watch the huge fire, smoke from which could be seen for miles away.
Transport for London was reporting severe delays on the Northern line this evening, though this is understood to be related to a power failure at Highgate.
Firefighters were called to the disused industrial park behind Allum Way at 9.27pm