By JOHN SEEWER

Crews continuing to search for debris from the deadly collision of a passenger jet and Army helicopter near Washington used a plane outfitted with lasers to scan the bottom of the Potomac River early Saturday, the National Transportation Safety Board said.

Large pieces of the jetliner and helicopter along with the remains of all 67 victims already were recovered earlier this week and crews now will spend the coming days looking for smaller debris before finishing the work in about a week.

A plane operated by the National Oceanic and Atmospheric Administration and equipped with laser scanning technology flew at low altitudes over the crash site. The lasers are used to penetrate the river’s surface and map the riverbed.

The NTSB said information collected will be part of its ongoing investigation into the Jan. 29 collision between the Army helicopter and an American Airlines flight over Washington, D.C. There were no survivors.

President Donald Trump on Thursday blamed the collision on what he called an “obsolete” computer system used by U.S. air traffic controllers and vowed to replace it.

NTSB officials told members of Congress that the helicopter’s advanced surveillance technology, which transmits aircraft location and other data to air traffic control and other aircraft, was turned off, Texas Republican Sen. Ted Cruz said Thursday.

Investigators are also looking into the altitude of the plane and helicopter, including whether the chopper was above its 200-foot (61-meter) flight ceiling. Investigators need to be able to examine the wreckage of the Black Hawk to get more precise information.

The crash was the deadliest in the U.S. since Nov. 12, 2001, when a jet slammed into a New York City neighborhood just after takeoff, killing all 260 people on board and five on the ground.