MIAMI (AP) -- Forecasters say Hurricane Gonzalo has strengthened overnight and is again a dangerous Category 4 storm as it barrels toward the small British island territory of Bermuda.

Hurricane Gonzalo, lower right. At 2 a.m. EDT Thursday (AP Photo/NOAA)

The U.S. National Hurricane Center in Miami says Gonzalo reached Category 4 strength early Thursday for the second time in two days while fluctuating in intensity.

It says Gonzalo is howling with maximum sustained winds of 140 mph (220 kpH) and is centered about 540 miles (865 kilometers) south-southwest of Bermuda. It's moving toward the north at 9 mph (15 kph) toward Bermuda, where a hurricane warning is in effect as the territory rushes to batten down.

The hurricane center says the eye of Gonzalo is expected to pass near Bermuda sometime Friday, and a dangerous storm surge is expected along with heavy rainfall.

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