Police have urged drivers to avoid the Sydenham Bypass in East Belfast after five vehicles were involved in a crash around 4pm.
The ambulance service and PSNI are in attendance and it is unclear at this stage if anyone sustained injuries.
One driver said: "The queues are already very long and the traffic is at a standstill. Drivers heading into the city are slowing down and drivers who had been heading on the Bangor bound carriageway are having to sit it out.
"There are three ambulance crews and a number of police cars on the hard shoulder dealing with the matter. Hopefully everyone involved is OK."
In a brief statement, a PSNI spokesperson said: "Motorists are being advised to expect delays on the Sydenham Bypass towards Holywood as police attend a five vehicle road traffic collision. Drivers are advised to seek an alternative route."
Meanwhile, obstruction on May Street in Belfast city centre has been moved to a bus lane and both right turn lanes are now passable with care.
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