Officials say the conditions of the Potomac River are complicating recovery efforts of the bodies of the 67 presumed dead in a mid-air collision between American Airlines flight 5342 from Wichita and a military Black Hawk helicopter.

Residents and visitors were told to not touch or remove debris from the Potomac River, as the investigation into the midair D.C. plane crash remains ongoing.

An airplane collided with a helicopter while trying to land at the Ronald Reagan Washington National Airport on Wednesday night, officials said.