PORTER HEIGHTS, Texas -

A Houston firefighter is dead after a woman who opened fire says that the firefighter was trying to break into her Montgomery County home.

The woman says she had no idea he was a firefighter, and says she had no idea that the man she heard trying to get inside of her front door was her next-door neighbor.

Investigators say the 64-year-old woman physically is doing alright, but emotionally she is shaken. At around 9:30 p.m. Monday, she says she heard a man fumbling around the front gate of her Porter Heights home on Youpon Lane. According to deputies, it sounded to her like he was trying to break in. She was home alone, so detectives say she grabbed her protection -- a revolver.

"At the time, she again told him to leave and that she was armed," said Sgt. Dan Zientek, with the Montgomery County Sheriff's Office.

After several verbal warnings, she pulled the trigger.

"She fired twice through the door, striking the person," Sgt. Zientek said.

The shots hit Samuel Keen, a four-year veteran with the Houston Fire Department. He was transported to Ben Taub Hospital, where he was pronounced dead. Neighbors say they are shocked and saddened.

"Obviously our thoughts and prayers go out to his entire family, and his extended family -- the Houston Fire Department," said HFD Chief Terry Garrison.

While deputies collected evidence, the question of motive began to surface and how he was able to get through the woman's gate.

"It's normally closed at all times. How he gained entry... he appeared to walk up to the yard without a vehicle," said Sgt. Zientek.

Detectives thought it was odd that if it was an attempted break-in, there was no evidence of a getaway car. But that's because the man's vehicle was parked in his driveway. Keen was the woman's next-door neighbor.

Investigators say earlier on St. Patrick's Day he was at a bar with friends and took a cab ride home. Unfortunately, the 27-year-old husband never made it home.

Earlier Tuesday across the city, firefighters had a moment of silence in Keen's honor.

Deputies say no charges were filed against the homeowner. Detectives say they are still interviewing witnesses and investigating the incident to prepare the case for presentation to a grand jury.