A young U.S. Marine from Foster City was killed Monday when his unit was attacked with grenades and gunfire in western Iraq just a few weeks after he arrived for combat duty.

Lance Cpl. Andrew Dang, who graduated less than two years ago from San Mateo's Aragon High School, was on a peacekeeping patrol in a volatile region known as the ``Sunni triangle,'' Marines spokesman Sgt. Charles Moore said Tuesday.

The 20-year-old died almost a year to the day after the war began, becoming one of the 582 U.S. soldiers reported killed so far in the conflict -- the first from San Mateo County.

News of Dang's death rippled through his tight-knit community, where friends and students at Aragon recalled him as a bright, hard-working student and accomplished athlete. He played on the varsity football and wrestling teams and helped inaugurate the school's cutting-edge robotics team.

Friends also remembered him as a deep thinker, evident in the quote from British novelist Iris Murdoch that Dang chose to place under his senior class yearbook picture: ``We live in a fantasy world, a world of illusion. The great task in life is to find reality.''

Dang graduated in 2002 in the top 10 percent of his class, Assistant Principal Jim Coe said, compiling a 3.7 grade-point average. He played defensive line for the football team and excelled even though he was smaller than many other linemen, at about 210 pounds, friends recalled.

On the school's robotics team, he helped build 400-pound robots that could perform tasks such as lifting objects and placing them in specified spots.

``It's always such a shock when you lose a student, and he's such a recent graduate, and so young,'' Coe said Tuesday. ``He was just an all-around great student and good person with a lot of accomplishments.''

Derek Kenmotsu, 20, Dang's longtime classmate who now attends the U.S. Military Academy at West Point, had returned to Foster City on Tuesday during spring break. He was recruiting students at Aragon when he heard the news about his buddy's death.

``I just can't believe he's gone,'' said Kenmotsu, who remembers Dang saying he wanted to join the Marines to learn engineering and eventually develop new weapon systems.

``It hits close to home,'' Kenmotsu said. ``It doesn't change my plans, but it makes me understand the dangers that are present.''

Flags flew at half-staff from Aragon High to the state Capitol in honor of Dang. Gov. Arnold Schwarzenegger issued a statement commending him.

``Andrew served our country with honor and distinction,'' the governor said. ``We should all be thankful for his sacrifice and admire his courage. Our thoughts and prayers go out to his family and friends.''

Dang's younger brother is a senior at Aragon, and another brother is a freshman at San Mateo High School, Kenmotsu said. Members of his family could not be reached Tuesday. The young Marine was not married.

Dang enlisted in the Marines last April, about a month after the Iraqi war began. He was sent to Camp Pendleton near San Diego and trained as a combat engineer. In November, he was assigned to a the 1st Combat Engineer Battalion, 1st Marine Division, 1st Expeditionary Force. His unit was sent between late February and early March to Iraq to replace soldiers from the Army's 82nd airborne division.

Though the circumstances of the attack were not clear, Moore said Dang and his unit were on a peacekeeping patrol near the city of Ar Ramadi -- an area predominantly of minority Sunni Muslims, who ruled Iraq and remain loyal to Saddam Hussein. There was no information on whether others in the patrol were wounded or killed.

Dang died decorated with the National Defense Service Medal, awarded for joining up and serving during a war.