FORT HOOD, Texas — As if going off to war, Maj. Nidal Malik Hasan cleaned out his apartment, gave leftover frozen broccoli to one neighbor and called another to thank him for his friendship — common courtesies and routines of the departing soldier.

Instead, authorities say, he went on the killing spree that left 13 people dead.

Investigators examined Hasan's computer, his home and his garbage yesterday to learn what motivated the suspect, who lay in a coma, shot four times in the frantic bloodletting. Hospital officials said some of the wounded had extremely serious injuries and might not survive.

The 39-year-old Army psychiatrist emerged as a study in contradictions: a polite man who stewed with discontent, a counselor who needed to be counseled himself, a professional healer now suspected of cutting down the fellow soldiers he was sworn to help.

Relatives said he felt harassed because of his Muslim faith but did not embrace extremism. Others were not so sure. A recent classmate said Hasan once gave a jarring presentation to students in which he argued the war on terrorism was a war against Islam, and "made himself a lightning rod for things" when he felt his religious beliefs were challenged.

Investigators were trying to piece together how and why Hasan allegedly gunned down his comrades in the worst case of violence on a military base in the U.S. The rampage unfolded at a center where some 300 unarmed soldiers were lined up for vaccines and eye tests.

Soldiers reported that the gunman shouted "Allahu Akbar!" — an Arabic phrase for "God is great!" — before opening fire Thursday, said Lt. Gen. Robert Cone, the post commander. He said officials had not confirmed Hasan made the comment.

The 30 wounded were dispersed among hospitals in central Texas. W. Roy Smythe, chairman of surgery at Scott and White Memorial Hospital, said several patients were still at "significant risk" of losing their lives. Army briefers told lawmakers in Washington eight other people were treated at a hospital for stress and trauma.

Army Col. John Rossi, deputy commander at Fort Hood, yesterday said 23 people remained hospitalized, about half still in intensive care. He praised the soldiers' quick actions during and after the shooting barrage, which he said saved lives.

Rossi said that the assailant fired more than 100 rounds and that his weapons were not military arms, but "privately owned weapons ... purchased locally."

Law enforcement sources in Washington, speaking on condition of anonymity, said records indicate Hasan in recent months bought the FN 5.7 pistol at a store called "Guns Galore" in Killeen, Texas.

Hasan, meanwhile, was transferred yesterday to the Brooke Army Medical Center at Fort Sam Houston in San Antonio. Rossi gave no indication of his condition except to say he was "not able to converse."

COMMUNITY MOURNS

In a vigil last night, husbands wrapped their arms around their wives, babies cried and old men in wheelchairs bowed their heads as several hundred people gathered at a stadium on the sprawling Army post, the country's largest. It was the first gathering of the community since the killings.

"Remember to keep breathing ... keep going," Chaplain Douglas Carver told the crowd, many wearing fatigues and black berets.

Earlier, 13 flag-draped coffins departed for Dover Air Force Base and the military's mortuary based in Delaware, Rossi said. Officials said the result of autopsies on the victims will be made available to the appropriate federal and military agencies that are probing Thursday's shooting. They will determine if any of the victims might have been hit by friendly fire, something Rossi all but dismissed.

Army Chief of Staff George Casey said he asked bases around the country to assess their security. He also said he was worried about a backlash against the thousands of Muslim soldiers serving dutifully in uniform.

Hasan was due to be deployed to Afghanistan, the Army said. Army spokeswoman Col. Cathy Abbott was uncertain when Hasan was to leave but he was in the preparation stage of deployment, which can take months.

In any event, the major was saying goodbyes and dispensing belongings to neighbors.

Jose Padilla, the owner of Hasan's apartment complex, said Hasan gave him notice two weeks ago that he was moving out this week.

"I cannot comprehend that the enemy was among us," Padilla said, as he teared up. "I feel a little guilt that I was basically giving housing to someone who is going to do so much destruction."

Neighbor Patricia Villa said Hasan came to her apartment the day of the shooting, and before, to give her vegetables, an air mattress, T-shirts, a Quran and offer her $60 to clean his Killeen, Texas, apartment after he left.

Jacqueline Harris, 44, who lives with her boyfriend, Willie Bell, in the apartment next door to Hasan, said he called Thursday at 5 a.m. and left a message.

"He just wanted to thank Willie for being a good friend and thank him for being there for him," Harris said. "That was it. We thought it was just a nice message to leave."

Bell said Hasan offered a farewell, saying, "Nice knowing you, old friend. I'm going to miss you."

VEHICLE SCRATCHED

According to a Killeen police report in August, an Army employee was charged with scratching Hasan's car, causing $1,000 in damage. Apartment manager John Thompson said the man charged was a soldier back from Iraq, who objected to Hasan's faith and ripped a bumper sticker off the major's car that said: "Allah is Love."

Kim Rosenthal, another neighbor, said Hasan didn't seem too upset by his scratched vehicle, even though it was damaged so badly that he got a new one. "He said it was Ramadan and that he had to forgive people," Rosenthal said. "He forgave him and moved on."

Hasan appeared less forgiving to Dr. Val Finnell when they were classmates in a 2007-08 master's public health program at the Uniformed Services University of the Health Sciences in Bethesda, Md.

He said that at a class presentation by public health students, at which topics like dry cleaning chemicals and house mold were discussed, Hasan talked about U.S. military actions as a war on Islam. Hasan made clear he was a "vociferous opponent" of U.S. wars in Muslim countries, Finnell said.

"He made himself a lightning rod for things," Finnell said. "No one picked on him because he was a Muslim."

Hasan is the Arlington, Va.-born son of Palestinian parents who ran a restaurant and bar in Roanoke, Va., from 1987 to 1995 and owned a small grocery store in that city.

His relatives in the West Bank said they had heard from family members that Hasan felt mistreated in the Army as a Muslim.

"He told (them) that as a Muslim committed to his prayers he was discriminated against and not treated as is fitting for an officer and American," said Mohammed Malik Hasan, 24, a cousin. "He hired a lawyer to get him a discharge."

Mohammed Hasan said outside his home in Ramallah that he heard about the shooting from a relative.

"I was surprised, honestly, because the guy and his brothers are so calm, and he, as I know, loves his work."