CORPUS CHRISTI, Texas — A Navy helicopter on a training mission went down in a fiery crash near a 971-foot-tall antenna tower, killing three crew members and critically injuring a fourth, a Navy spokesman said Thursday.

Investigators were examining the wreckage from the Wednesday night crash, including a large piece that could be seen at the base of the tower. Authorities would not say whether the helicopter, an MH-53 Sea Dragon, hit the tower, but a television station executive said he thinks his station's tower was hit.

Don Dunlap, president and general manager of South Texas Public Broadcasting System, said it appeared the helicopter struck the tower about 50 feet from its top. He said parts of the antenna were on the ground and that the beacon on top had been knocked off.

"It was a horrific scene out there," Dunlap, whose station was knocked off the air for 14 hours, told KEDT radio. "Pieces of that helicopter were everywhere."

Investigators were trying to determine what caused the wreck. The investigation could take months, Naval Air Station Corpus Christi spokesman Bob Torres said.

A Navy spokesman said it was extremely foggy at the time of the accident, which occurred about 4 miles south of Corpus Christi in an area made up largely of flat farmland.

"We couldn't see 200 feet around that tower when I got out there," Dunlap said.

Johnny Rivera, 73, who lives about a mile from the crash site, jumped up when he heard the impact.

"Boom! We heard it," said Rivera, an ex-helicopter mechanic at the Army depot on Naval Air Station Corpus Christi. "There was a whole lot of fire."

The injured crew member was taken to a hospital, where he was in critical condition, said Ed Mickey, a spokesman for the Naval Mine and Anti-Submarine Warfare Command.

The helicopter was part of Helicopter Mine Countermeasures Squadron 15 out of Naval Air Station Corpus Christi, Mickey said.

The crew members' names will be released Friday, after victims' next-of-kin are notified, said Lt. Cmdr. David Nunnally, spokesman for Commander Naval Air Force Atlantic in Norfolk, Va.

J.D. Batten, who lives about two miles from the crash site, told the Corpus Christi Caller-Times he was walking near his property's front gate when he heard a helicopter overhead.

"Suddenly I saw a red-glowing fireball shoot hundreds of feet up into the air," he said. "I heard a giant boom a second later. It was then dead silent and I couldn't hear the helicopter anymore."

The crash caused a fire, but firefighters extinguished the flames.

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Associated Press writers Terry Wallace and Diana Heidgerd in Dallas contributed to this report.