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.

The National Transportation Safety Board has released an update on the status of its investigation into the midair collision that occurred on Jan. 29 near Ronald Reagan National Airport, revealing that all major pieces from both the airplane and the helicopter involved have now been recovered from the Potomac River.

Investigators searching for wreckage from last week’s deadly midair collision between a US military Black Hawk helicopter and an American Airlines plane near Washington, DC, conducted an overnight scan of the Potomac River where the aircraft fell using advanced imaging technology to map the riverbed and locate debris.