It's unclear if 29-year-old Carnell Marcus Moore shot himself or if he was killed by a Homeland Security agent at George H. W. Bush Intercontinental Airport.

Houston police say shortly after 1:30 p.m. Thursday, Moore fired at least one shot into the air in Terminal B.

Police say the agent asked Moore to drop the gun, but they say he refused.

It appears the agent then fired his weapon at the same time Moore may have shot himself.

Police say Moore left a suicide note saying he was taking his life because, "The monster within is getting stronger."

But when we visited where he lived on Magnolia Street, neighbors could not believe what we were telling them about Moore.

We first stopped at the home where Moore lived with his sister. We knocked on the door and naturally she could not comprehend why a reporter would be seeking comment from her at such a tragic time.

She said, "Are you crazy, what would you say if it was your brother."

Moore's across the street neighbor did have plenty to say about the 29-year-old, and it was all positive.

Byron Collier called him calm and quiet. Collier said you would think he was a preacher.

Collier went on to say, "I just can't believe that young man did a stunt like that."

But Moore seems to have had a dark side secret from those who surrounded him.

The day before his death, Moore posted on Facebook: "This life will crash tomorrow!"

He also posted, "I recently had the chance of staring death in the face, and she was beautiful."

At the Honey Stop convenience store, where he once worked, and where his dad is still employed, disbelief and sadness as well.

Richard Johnson, a customer at the store, said he shook Moore's hand Wednesday.

Moore did not have a criminal record.

Neighbors say FBI agents spent three hours at Moore's house, looking for possible evidence.

At the airport, police recovered the handgun Moore used, and found a rifle inside his truck.

Police say it could be a couple of days before they trace information on those weapons.

We've also learned that Moore did attend the Lamar Institute of Technology between 2007 and 2009.

But LIT's public information officer tells us she's unaware if Moore graduated.