A Delta IV rocket carrying a classified spacecraft was successfully launched from Florida's Cape Canaveral Space Launch Complex 37, officials said.

The United Launch Alliance said the liftoff occurred at 6:38 p.m. EST Friday following a half-hour delay caused by unacceptable upper-level wind data from weather balloons.

The 21-story rocket carried a classified National Reconnaissance Office satellite dubbed "Gryphon" and was the fourth NRO mission launched since September.

The launch was the seventh for the two-stage, liquid-hydrogen and liquid-oxygen fueled Delta IV M+(4-2) configuration featuring a single common core booster first stage supported by two solid rocket motors, Florida Today reported.

Official details of the mission are classified, but the payload has been identified as an NROL-27 communications satellite, which will form part of the Satellite Data System, a constellation of spacecraft used to relay data from other NRO satellites to the ground.