WASHINGTON (AP) — About 10 members of an Army unit based at Fort Lewis, Wash., are under investigation for as many as three civilian deaths in Afghanistan, along with other potential wrongdoing, a senior military official said Monday.

The official did not have details of the investigation but confirmed that the 5th Stryker Brigade was under scrutiny.

The official spoke on condition of anonymity because he was not authorized to discuss details of an investigation being conducted in Afghanistan. CNN first reported Monday that at least 10 members of the Stryker unit were being investigated.

The Stryker brigade, operating in Kandahar province in southern Afghanistan, has suffered heavy casualties in the fight against Taliban insurgents. It has received congratulatory visits in recent months from Joint Chiefs of Staff Chairman Adm. Mike Mullen and Defense Secretary Robert Gates.

The military said last week it was investigating allegations that a "small number" of U.S. soldiers were responsible for the unlawful deaths of as many as three Afghan civilians.

The statement said the allegations also included illegal drug use, assault and conspiracy. It said no charges had been filed but one soldier has been placed in pretrial confinement.

The Army's Criminal Investigation Command began the investigation after receiving credible information from the soldiers' unit earlier this month.