FORT HOOD, Texas -- Fort Hood nurses administering smallpox vaccines and doing medical tests for deploying soldiers suddenly became medics when their workplace turned into a combat zone during last year's shooting rampage.

They slipped on the floor covered with blood and bullets while rushing to help, nurses and other workers testified during a military hearing for the Army psychiatrist charged in the shootings.

One soldier testified Tuesday about how she tried to help Sgt. Amy Krueger.

"I was talking to her, trying to find out where she'd been shot. It was hard to tell because there was blood everywhere," Staff Sgt. Helen Kennedy sobbed. "The EMTs came in ... and threw me a black tag ... (which means) she was not expected to live, but I continued to work on her. She died."

The Article 32 hearing is being held to determine whether Maj. Nidal Hasan will stand trial on 13 counts of premeditated murder and 32 counts of attempted premeditated murder in the Nov. 5 shootings.

Testimony was expected to continue Wednesday.

Hasan has attended every day of the hearing, now in its second week, in a wheelchair. The 40-year-old American-born Muslim is paralyzed from the waist down from police gunfire that ended the onslaught.

Sgt. 1st Class Maria Guerra, a manager of the building where soldiers get vaccines and other medical tests before deployment, testified Tuesday that she emerged from her office after the rampage to find "just bodies all over the floor -- bodies and blood. No one was moving."

After locking the doors so the gunman would not re-enter, Guerra shouted out that there were mass casualties. Nurses and other workers -- mostly civilians -- crawled from beneath the desks and cubicles where they'd been hiding and saw the carnage.

They removed some of the soldiers' clothing, frantically trying to find bullet wounds. They took off their belts and used them as tourniquets on soldiers' arms and legs.

Sgt. 1st Class Ingar Campbell, now retired, rushed out of her case management office and saw a wounded soldier who, just moments before the shooting, had been waiting to get a waiver for his sleep apnea so he could deploy. She rushed to help Staff Sgt. Justin DeCrow, but "he died in my arms," she testified.

Guerra saw that a few soldiers were already dead, but some nurses kept trying to revive them. Guerra said that she took a marker and wrote on their foreheads: "D" for deceased and the time, "13:25."

Several witnesses at the hearing have said the gunman in an Army combat uniform shouted "Allahu Akbar!" -- "God is great!" in Arabic -- then opened fired in a crowded waiting area. They say he kept firing rapidly, pausing only to reload, and shot people as they hid under tables or curled up in chairs -- even shooting soldiers after they fled outside.

Guerra and a nurse testified Tuesday that they recognized Hasan as the gunman because about a week before the shooting, the major had been uncooperative while discussing vaccinations at the medical center. About 30 civilians worked in the building and 15 soldiers, according to testimony.

Also Tuesday, the court heard recording of two 911 calls made by two nurses: one barricaded in her office and another hiding under a desk.

"The shooter just came in and shot soldiers and started shooting!" a frantic Shemaka Hairston told the 911 operator, the call punctuated by screams and a rapid series of gunshots in the background.

At some point after the hearing, Col. James L. Pohl, the investigating officer in the case, will recommend whether Hasan should go to trial. That decision -- and whether the Army will seek the death penalty -- ultimately will be made by Fort Hood's commanding general.

Hasan remains jailed. There is no bail in the military justice system.