UPDATE: Hillsborough mayor says of firefighters 'They are in for a long night'.

HILLSBOROUGH - Firefighters are battling a five-alarm blaze at a warehouse located adjacent to Harold Docherty Memorial Park off Route 206.

The fire was first reported shortly before 3 p.m. and just after 3:45 p.m. police reported Route 206 is being closed in both directions south of Brooks Boulevard, according to 511nj.org.

The complex is made up of four large multi-tenant warehouses and four smaller warehouse buildings. The Somerset County Emergency Services complex, including the Somerset County Police Academy.

Witnesses said the fire started near USA Container Co., Inc. Photos on the company's website show the Hillsborough warehouse filled with bulk food storage containers.

As of 6 p.m. there are reports that the fire is spreading toward warehouses that were not part of the initial blaze.

At 5 p.m. firefighters had been ordered to move back from the warehouses as the fire is spreading, according to Hillsborough Township police Det. Richard Evans. Thick black smoke can be seen for miles and is clearly visible on weather radar. The radar shows the smoke spreading from Hillsborough in Somerset County east some 50 miles to Long Branch in Monmouth County.

Police also report that power has been turned off in the area of the fire and Roycefield Road is closed between Valley and Roycefield roads.

Franklin Township sent an advisory to residents that heavy smoke can be seen and "loud noises that are best described as explosions."

According to Hillsborough Township Health Officer Dr. Glen Belnay the smoke is believed to be nontoxic. Residents of Camplain and Sunnymead roads and Brooks Boulevard are asked to stay in their homes and keep windows closed.

"Our guys are out there working as best as they can to keep it contained, and wind is a concern," Hillsborough Mayor Frank DelCore said. "It's certainly spread at this point and we've shut down power to the Route 206 area."

Firefighters were sent to the nearby Somerset County Police Academy to protect it from the fire and crews have spread out to put out brush fires caused by burning embers.

Traffic is delayed in both directions from Triangle Road to Dukes Parkway West. There are also delays on Camplain Road and Brooks Boulevard into Manville. Delays are being reported on Dukes Parkway West in Hillsborough and South and North Main Street in Manville.

A representative of the Manville Fire Department said it is believed the warehouses were evacuated.

Firefighters from Hillsborough, Manville, Raritan Township in Hunterdon County, Somerville and Montgomery are among the fire companies on scene.