Douglas Ealey Jr., the popular Prince George's County student leader who took his life Monday, was buried yesterday at Arlington National Cemetery at a ceremony attended by hundreds of his teen-aged friends, who remain shocked and baffled by his death.

"Why are we here?" asked the Rev. Louis Shockley, a family friend who took the occasion of Ealey's eulogy at the funeral services earlier in the day to ponder the mystery of the suicide.

"The ultimate question," the clergyman said, is "why would someone who had so much . . . want to make such a decision?"

Ealey, 17, a Suitland High School senior enrolled in courses for the academically gifted, was the county's student representative to the Board of Education this year. He shot himself Monday morning moments before his mother, Patricia, reached his bedroom.

Police said she had rushed home from work after being alerted by a close friend of her son's, who had received a note hinting that the youth was contemplating suicide.

Zion Baptist Church in Northeast Washington, the site of Ealey's funeral, was filled to capacity, causing the overflow crowd to spill into the foyer and line the aisles in folding chairs.

The gathering included County Council members, school Superintendent John A. Murphy and members of the Board of Education, but was made up primarily of adolescents, many of them visibly overcome with the sadness of their friend's death.

Suitland High School had closed early in order to allow students to attend the services. After the funeral service, many of the students filed quietly past Ealey's open casket, then left the church shaken, sobbing and comforting each other.

Seven members of the Suitland Junior ROTC served as pallbearers, maintaining their military bearing while standing at uniformed attention outside the church before the service.

But most of the seven in the honor guard lost their composure during the service and were in tears as they carried their friend's casket to the waiting hearse.

Ealey was buried in the same plot as his father, Douglas Ealey, who was killed while on active duty in Vietnam when his son was a year old.

After the procession of nearly a hundred cars drove away from the burial site, a small group of Ealey's closest friends remained in the autumn chill, their arms entwined as they stood around his casket.

"I don't have any answers to offer today," Shockley said at the funeral service. "Douglas, you left us so quickly, we didn't get to find out what the problems were. We'll go on wondering, forever and ever, how and why."

Ealey's friends and teachers said that the youth had shown no signs of depression before his death.

"He was happy, always making little side jokes," said Stuart Rosenberg, 15, who served with Ealey on the county's regional student government. "He had a lot of friends."

Rosenberg said that Ealey's friends reacted to his death with "total, utter shock," and added: "It's like you never can imagine him doing anything like this, because he seemed the total nonviolent type."

To those who knew him, Ealey's death brought home what experts describe as an epidemic of suicides among adolescents. Teen-age suicides have tripled since 1950, according to the National Institute of Mental Health.

Shockley, chaplain at the University of Maryland, told the funeral crowd that just a week ago he had been called to counsel a female student who was close to taking her own life. He said that the girl told him: "Everybody thinks I've got it all together. Nobody knows the pain I've got inside. How can I go on?"

"The verdict is still out on that one," said Shockley, "but the verdict is in on Doug."

Relatives and friends said that Ealey frequently had pondered the impermanence of life. His favorite poem, according to his family, was a verse by Robert Frost, which was read at the funeral by his older sister and only sibling, Tamara:

Nature's first green is gold,

Her hardest hue to hold.

Her early leaf's a flower;

But only so an hour.

Then leaf subsides to leaf.

So Eden sank to grief,

So dawn goes down to day.

Nothing gold can stay.