FORT HOOD, Texas — Soldiers who witnessed the shooting rampage at Fort Hood that left 13 people dead reported that the gunman shouted "Allahu Akbar!" before opening fire, the base commander said Friday.

Lt. Gen. Robert Cone said officials had not yet confirmed that the suspected shooter, Maj. Nidal Malik Hasan, made the comment, which is Arabic for "God is great!" before the rampage Thursday, which left 30 people wounded, including the gunman.

An imam from a mosque Hasan regularly attended said Hasan, a lifelong Muslim, was a committed soldier, gave no sign of extremist beliefs and regularly wore his uniform at prayers.

Cone said Hasan was hospitalized in stable condition and that investigators hope to interrogate him as soon as possible. In the early chaos after the shootings, authorities believed they had killed him, only to discover later that he had survived.

Cone said Hasan was not known to be a threat or risk. He acknowledged that it was "counterintuitive" that a single shooter could kill and injure so many people. But he said the massacre occurred in "close quarters."

"With ricochet fire, he was able to injure that number of people," Cone said. Authorities are investigating whether Hasan's weapons were properly registered with the military.

The motive for the shooting wasn't clear, but Hasan was apparently set to deploy soon and had expressed some anger about the wars in Iraq and Afghanistan. Sen. Kay Bailey Hutchison, a Texas Republican, said generals at Fort Hood told her that Hasan was about to deploy overseas. In Washington, sources said he would be sent to Iraq.

Lee said Hasan had hoped Obama would pull troops out of Afghanistan and Iraq and got into frequent arguments with others in the military who supported the wars.

Officials are not ruling out the possibility that some of the casualties may have been victims of "friendly fire," that in the mayhem and confusion at the shooting scene some of the responding military officials may have shot some of the victims.

The gunfire broke out around 1:30 p.m. at the Soldier Readiness Center, where soldiers who are about to be deployed or who are returning undergo medical screening. Nearby, some soldiers were readying to head into a graduation ceremony for troops and families who had recently earned degrees.

Pastor Greg Schannep had just parked his car along the side of the theater and was about to head into the ceremony when a man in uniform approached him.

"Sir, they are opening fire over there!" the man told him. At first, he thought it was a training exercise — then heard three volleys and saw people running. As the man who warned him about the shots ran away, he could see the man's back was bloodied from a wound.

Schannep said police and medical and other emergency personnel were on the scene in an instant, telling people to get inside the theater. The post went into lockdown while a search began for a suspect and emergency workers began trying to treat the wounded. Some soldiers rushed to treat their injured colleagues by ripping their uniforms into makeshift bandages to treat their wounds.

Video from the scene showed police patrolling the area with handguns and rifles, ducking behind buildings for cover. Sirens could be heard wailing while a woman's voice on a public-address system urged people to take cover. Schools on the base went into lockdown, and family members trying to find out what was happening inside found cell phone lines jammed or busy.

"I was confused and just shocked," said Spc. Jerry Richard, 27, who works at the center but was not on duty during the shooting. "Overseas you are ready for it. But here you can't even defend yourself."

The wounded were dispersed among hospitals in central Texas, Cone said. Their identities and the identities of the dead were not immediately released.

The bodies of the victims would be taken to Dover Air Force Base in Delaware for autopsies and forensic tests, said a U.S. official who spoke on condition of anonymity to discuss matters that were under investigation.

There also will be a ceremony at the air base to honor the dead.

For six years before reporting for duty at Fort Hood in July, Hasan worked at the Walter Reed Army Medical Center pursuing a career in psychiatry, as an intern, a resident and, last year, a fellow in disaster and preventive psychiatry. The 39-year-old Army major received his medical degree from the military's Uniformed Services University of the Health Sciences in Bethesda, Maryland, in 2001.

But his record wasn't sterling. At Walter Reed, he received a poor performance evaluation, according to an official who spoke on condition of anonymity because he was not authorized to discuss the case publicly. And while he was an intern, Hasan had some "difficulties" that required counseling and extra supervision, said Dr. Thomas Grieger, who was the training director at the time.

Faizul Khan, a former imam at a mosque Hasan attended in Silver Spring, Maryland, said "I got the impression that he was a committed soldier." He said Hasan attended prayers regularly at the mosque and was a lifelong Muslim. He spoke often with Hasan about Hasan's desire for a wife.

In an interview with The Washington Post, Hasan's aunt, Noel Hasan of Falls Church, Virginia, said he had been harassed about being a Muslim in the years after the Sept. 11, 2001, terror attacks, and he wanted out of the Army.

"Some people can take it and some people cannot," she said. "He had listened to all of that and he wanted out of the military."

At least six months ago, Hasan came to the attention of law enforcement officials because of Internet postings about suicide bombings and other threats, including posts that equated suicide bombers to soldiers who throw themselves on a grenade to save the lives of their comrades.

Investigators had not determined for certain whether Hasan was the author of the posting, and a formal investigation had not been opened before the shooting, said law enforcement officials who spoke on condition of anonymity because they are not authorized to discuss the case.

The FBI, local police and other agencies searched Hasan's apartment Thursday night after evacuating the complex in Killeen, said city spokeswoman Hilary Shine. She referred questions about what was found to the FBI. The FBI in Dallas referred questions to a spokesman who was not immediately available early Friday morning.