FORT HOOD, Texas, Nov 8, 2009 (AFP) - Carrying homemade meals, the four  volunteers knocked on the door of a Fort Hood house, home to a woman whose husband was among those injured in a bloody attack here this week.

Sergeant Alvin Howard, 37, was preparing to deploy to Afghanistan in January, but after being shot in the shoulder during Thursday's shocking violence he is now recovering in the hospital.

At home, his wife Kanesha and daughters Alanna and Kristen are left to rely on the support of their community.

More than 200 investigators were working around-the-clock on Sunday to uncover how and why 39-year-old army psychiatrist Nidal Hasan allegedly went on the rampage at this military base, killing 13 people and injuring 30 others.

At present investigators believe Hasan was the lone perpetrator of the attack, using two of his own handguns to fire more than 100 rounds at a troop processing center - building 42003.

"All evidence at this point indicates the suspect allegedly acted alone," said army investigation spokesman, Chris Grey, appearing to strike down any theories that Hasan was part of a radical Islamist sleeper-cell.

At home, Kanesha Howard, Alanna, 9 and Kristen, 7, are still trying to process the violence.

"I was watching the news and they mentioned the center where he was supposed to be at the time. I was afraid, I was scared,"  Kanesha Howard said, speaking on her doorstep.

"How can this be happening back at home" she added, echoing a question posed by many here who understand the risks posed by combat zones, but never expected to experience such violence on the military base that is their home.

"I worry about my daughters' safety," she said.

Alanna, a little shy before all the photographers and reporters, described visiting her father in the hospital with her younger sister Kristen.

"She started crying when we were at the hospital because she had never seen our dad bandaged up like that," she said.

"We hugged him and gave him a kiss on the cheek."

"People have been very supportive, the unit has been very supportive, everybody's been very helpful," said Kanesha Howard.

"I just want to say thank you all, my prayers go out to the families who lost...," she said, her voice cracking as she broke into tears, unable to finish the sentence.

Sergeant Howard belongs to a battalion of combat engineers that lost four members in the carnage Thursday when Army psychiatrist Nidal Malik Hasan opened fire at this Texas military base.

Members of the unit and their families, seeking to show their support, brought homemade meals, fruit and soda to the relatives of those injured or killed in the massacre.

"I brought spaghetti," said Misty Wright, a young woman whose husband is in the army. "We didn't know any of the victims but we are still shaken," she said.

Casey Andrysiak, wife of the engineer battalion's commander, pronounced the outpouring of support "phenomenal."

"We got immediate e-mails, phone calls, deliveries, gift cards," she said as she accompanied her two-year-old son who was carrying a hot meal they planned to contribute to a family.

The army's Criminal Investigation Command has formally called for witnesses to the attack to come forward, and requested clothes or other personal effects that could contain gunshot residue, or any items to help put together a ballistic portrait of Thursday?s fateful events.

Meanwhile, the faithful flocked from all four corners of the base, under a gray sky and a fine drizzle, to attend religious services where the rampage was on everyone's mind.

"This has been a truly horrific last three days and every person has been touched in some way by this tragedy," said garrison chaplain Colonel Frank Jackson, who told worshipers to look to God for answers.

"All those around us search for meaning, answers and for someone to blame and it's so frustrating. Today we pause to hear from you. You are a refuge and a hope," he said.

In a pew, a soldier began to cry.

At the Comanche chapel, a largely African-American congregation sought refuge from the devastation in gospel singing on God's glory.

"Our focus today is on resiliency. The army is strong, we are focused on recovery. This morning I am focusing on getting through," said chaplain Captain Jason Black.

"I guess forgiveness is always an aspect when there is something like this but that is not the direct theme of my  message this morning."

The man believed to be responsible for the carnage, who was shot by a female civilian police officer now being hailed as a heroine, remains in intensive care but has been taken off a ventilator.