Chattanooga: Hailey Bureau still recalls the quote her high school classmate Muhammad Youssef Abdulazeez selected for his yearbook photo: "My name causes national security alerts. What does yours do?"

Abdul azeez was apparently borrowing a wisecrack from a well-known American Muslim blogger, and Bureau said it was considered a joke at the time.

"Now it's very morbid," she said, a day after the 24-year-old Kuwait-born Abdulazeez opened fire on two U.S. military sites in Chattanooga in an attack that left four Marines dead and raised the specter of terrorism on American soil.

A picture emerged Friday of Abdulazeez as a likable, outgoing young man who enjoyed a laugh, made the wrestling team and seemed "as Americanized as anyone else," yet was clearly aware of what set him apart at his Chattanooga high school.

What's not clear — to counterterrorism investigators and to neighbors and former classmates — is what set him on the path to violence that ended with him being gunned down by police.

Abdulazeez did not appear to have been on federal authorities' radar before the bloodshed Thursday, officials said. But now counterterrorism investigators are taking a deep look at his online activities and foreign travel, searching for clues to his political contacts or influences.

"It would be premature to speculate on exactly why the shooter did what he did," FBI agent Ed Reinhold said. "However, we are conducting a thorough investigation to determine whether this person acted alone or was inspired or directed."

In the quiet neighborhood in Hixson, Tennessee, where Abdulazeez lived with his parents in a two-story home, residents and former classmates sketched a picture of an utterly ordinary suburban existence. They said they would see him walking along the wide streets or doing yard work. One neighbor recalled Abdulazeez giving him a ride home when he became stranded in a snowstorm.

"It's kind of a general consensus from people that interacted with him that he was just your average citizen there in the neighborhood. There was no reason to suspect anything otherwise," said Ken Smith, a city councilman.

As ordinary as the Abdulazeez family appeared on the outside, court documents allege it was an abusive and turbulent household.

Abdulazeez's mother, Rasmia Ibrahim Abdulazeez, filed a divorce complaint in 2009 accusing her husband, Youssuf Saed Abdulazeez, of beating her repeatedly in front of their children and sexually assaulting her. She also accused him of "striking and berating" the children without provocation.

Weeks later, the couple agreed to reconcile, with the father consenting to go to counseling.

Abdulazeez graduated from Red Bank High School in Chattanooga, where he was on the wrestling team. A fellow Red Bank High graduate, Hussnain Javid, said Abdulazeez was "very outgoing," adding: "Everyone knew of him."

"Obviously something has happened since then," said Sam Plank, who graduated two years ahead of Abdulazeez but hadn't crossed paths with him since 2006. "He was as Americanized as anyone else. At least that's what it seemed like to me."

Bureau, 25, said she and Abdulazeez often sat next to each other because their last names were close alphabetically. She said she broke down Thursday when she learned Abdulazeez was the gunman, saying, "It's so shocking. I imagine him the way I knew him then, laughing and smiling."

Two friends of Abdulazeez who spoke to him within days of the shooting said Friday that he appeared upbeat and expressed excitement about the future of his new job — giving no outward signs of any violent plans.

Ahmed Saleen Islam, 26, knew Abdulazeez through the Islamic Society of Greater Chattanooga. He remembers seeing his friend at the mosque two or three nights before the shootings.

"Everything seemed fined. He was normal. He was telling me work was going great," Islam said. "We are so shocked and angry. We wish he would have come to us."

Bilal Sheikh, 25, had known Abdulazeez since they were teenagers, and they often played basketball together. He saw his friend at the mosque last weekend, as they came to pray and as part of the services to celebrate Ramadan.

Both men said that in the years they had known Abdulazeez, he never expressed any negative feelings about the United States or members of the military.

"He never said anything that would have been a red flag," Sheikh said. "I have so many questions in my head. I want to know why? What made him crack all of a sudden? It's mindboggling."

Abdulazeez got an engineering degree from the University of Tennessee at Chattanooga in 2012 and worked as an intern a few years ago at the Tennessee Valley Authority, the federally owned utility that operates power plants and dams across the South.

He was conditionally hired as an engineer at the Perry nuclear power plant near Cleveland and spent 10 days there before he was let go in May 2013 because he failed a background check, said Todd Schneider, a FirstEnergy Corp. spokesman. Schneider would not say why he failed.

Later Friday, a federal official who had been briefed on the matter told The Associated Press that Abdulazeez was dismissed because he failed a drug test. The official spoke on condition of anonymity because of the ongoing law enforcement investigation.

"He worked in an administrative building," Schneider said. "He was never allowed in the protected area of the plant near the reactor."

For the past three months, Abdulazeez had been working at Superior Essex Inc., which designs and makes wire and cable products.

In April, he was arrested on a drunken driving charge, and a mugshot showed him with a bushy beard.

Karen Jones, who lived next to the family for 14 years, said she was somewhat surprised last weekend by his appearance when she saw him walking with another man in woods behind the house, where he liked to shoot pellet guns at a red target suspended in a tree.

"He had this big beard, which was not how he used to be," Jones said. She said he was typically clean-shaven.

The women of the family always wore head coverings in accordance with their Muslim faith, Jones said.

The official Kuwait News Agency on Friday quoted the Interior Ministry as saying that while Abdulazeez was born in Kuwait, he was of Jordanian origin.

A U.S. official who was not authorized to discuss the case and spoke on condition of anonymity said that Abdulazeez was in Jordan last year for months, and that those travels and anyone he met with are being looked at as part of the terrorism investigation.

In recent months, U.S. counterterrorism authorities have been warning of the danger of attacks by individuals inspired but not necessarily directed by the Islamic State group. Officials have said they have disrupted several such lone-wolf plots.

But the FBI's Reinhold said Friday that so far, there is "no indication he was inspired by or directed by" ISIS or other groups.

The gunman on Thursday sprayed gunfire at a military recruiting center at a strip mall, then shot up a Navy-Marine training center a few miles away.

More details of the attack emerged Friday, with Reinhold saying Abdulazeez was armed with at least one handgun and two long guns — which means a rifle or a shotgun. Some of the weapons were bought legally, some may not have been, Reinhold said.

The gunman was also wearing a vest designed to hold extra ammunition, Reinhold said.

The dead Marines were identified as Gunnery Sgt. Thomas J. Sullivan of Hampden, Massachusetts; Staff Sgt. David A. Wyatt of Burke, North Carolina; Sgt. Carson A. Holmquist of Polk, Wisconsin; and Lance Cpl. Squire K. "Skip" Wells of Cobb County, Georgia. Sullivan, Wyatt and Holmquist had served in Iraq, Afghanistan or both.

An unidentified sailor seriously wounded in the attack remained hospitalized.

Troops inside military recruiting stations are unarmed, largely because of legal restrictions. Gen. Ray Odierno, the Army's chief of staff, said security at such installations will be reviewed in light of the attack.

But he added: "I think we have to be careful about over-arming ourselves." He said there is a danger of "accidental discharges and everything else that goes along with having weapons that are loaded that causes injuries."

On Friday, Gwen Gott added purple ribbons and a flag to a makeshift memorial taking shape outside the recruiting station.

"I love the service. Without them, where would we be as a country?" Gott said.