Following a helicopter crash on Fort Carson last week, most aviation operations are back to normal.

The 4th Combat Aviation Brigade is the only unit with aircraft at the base and most of it returned to regular flight operations Wednesday, Fort Carson said in a statement.

Two soldiers suffered minor injuries in the crash last week during routine training, prompting the grounding of all aircraft at the base.

The 4th Combat Aviation Brigade is working with the U.S. Army Combat Readiness Center and the U.S. Army Aviation Center of Excellence to determine the cause of the accident and develop a plan to return to full flight operations, the statement said.

The crash last week was the latest in a string nationally.

In February, Apache helicopters with the National Guard crashed twice.

On Feb. 12, an AH-64D Apache helicopter crashed in Utah injuring two. Then on Feb. 23, four national guardsmen died when the same type of helicopter crashed in Mississippi.

The National Guard Bureau grounded all its helicopter pilots following the crash.

As pilots have completed required training they have been allowed to resume flying, the National Guard said in a response to questions.

As of this week, 90% of Army National Guard aviators had completed the required training.

“Investigations into the incidents are ongoing and we cannot give any proximate cause, trends, or patterns until those investigations are complete,” the statement said.