The staffing at the air control tower at Reagan National Airport was "not normal" when an American Airlines plane and Army helicopter collided on Wednesday night, a report shows.

U.S. authorities said on Thursday it was not yet clear why a regional jet crashed into a U.S. Army helicopter at a Washington airport, killing 67 people in the deadliest U.S. air disaster in more than 20 years.

The airspace around Ronald Reagan Washington National Airport has long been problematic due to heavy military and commercial flight activity in the nation’s capital, according to industry insiders.

A preliminary safety report from the Federal Aviation Administration reportedly found that air traffic control staffing was abnormally low at Ronald Reagan Washington National Airport on the evening of Wednesday, Jan. 29, according to The New York Times, which obtained a copy of the report.

Two New England mothers and their children were among the 67 victims killed in the midair collision between an Army helicopter and an American Airlines flight over Ronald Reagan National Airport Wednesday night.

The crash near Reagan National Airport has renewed questions about the airport's flight load, considering its small size, among other issues.

Law enforcement and other officials say an aircraft went down near Ronald Reagan National Airport, and all takeoffs and landings have been halted.

An American Airlines jet from Wichita with 60 passengers and four crew members aboard collided Wednesday with an Army helicopter while landing at Ronald Reagan National Airport near Washington, prompt

A midair collision between an Army helicopter and an American Airlines flight from Kansas killed all 67 people aboard the two aircraft. That was the word from authorities Thursday as they scrutinized the actions of the military pilot after the country’s deadliest aviation disaster in almost a quarter century.

Sam Lilley, the pilot on the fatal American Airlines crash, was supposed to get married this fall according to his father