Robinson R44

Robinson R44 helicopter as Marsan Aviation Inc., of Wilmington, Del. Telephone messages weren’t immediately returned early Friday by an attorney for Marsan listed in FAA records. The aircraft was engulfed when firefighters arrived at the scene minutes after receiving a call at 10:30 p.m. Thursday, said Washington County emergency services director Kevin Lewis. No vehicles on the highway were hit when the helicopter smashed into the eastbound lanes of Interstate 70. All four aboard the helicopter were killed, though there were no injuries on the ground.

Three people who worked for Advanced Helicopter Concepts in Frederick and a passenger were killed in the crash, one of its instructors, Gary Smith, said Friday morning. He said the company had suffered a “huge loss.” “We thank everyone for their support and understanding during this difficult time,” he said, declining to release further details. Smith said the company was cooperating with National Transportation Safety Board investigators. The company trains pilots, takes photographers on aerial tours and fixes and sells helicopters, according to its Web site.

Advanced Helicopter Concepts’ office sits at the end of a hangar at Frederick Municipal Airport, where small planes could be seen taking off and landing Friday morning. Several cars were parked outside the office. Visibility was somewhat limited by fog at the time of the crash, but it wasn’t clear if weather played a role, Lewis said. Storms had passed through the area earlier in the night. Lewis said a witness saw the craft flying low when a bright arc of electricity flashed in the air, apparently caused by the helicopter striking a power line. It wasn’t clear if the craft was already on its way down when it hit the lines.