GLENDALE, AZ - Police and federal agents are investigating an explosion outside a Glendale home early Wednesday morning.
Authorities say someone left two improvised pipe bombs in the driveway. One detonated damaging two cars, the home's garage and part of the roof.
David Miller lives blocks away, but said the blast sent him and his neighbors clamoring out of their homes.
"I heard a very loud boom, my dogs come running into the bedroom, I knew from previous (explosions) where to go, cause it sounded like another explosion," Miller said.
The second device did not detonate, but the force of the blast from the first pipe bomb sent it sailing into a neighboring home owned by Daa Neuyen.
ABC15 camera's were there when Neuyen entered his home for the first time to survey the damage.
"It's broken window," said Neuyen as glass came crashing down when he pulled open his blind.
The pipe bomb traveled through the window, down a hallway, scraping the wall as it traveled and then pierced through two walls before lodging in an outer wall.
It left a nearly perfect cylinder looking silhouette cut out in the walls.
"This is the second time I've been hit," said Neuyen who described the first time a bomb intended for his neighbor damaged his home.
Neuyen is now selling his home.
Lt. Johnny Arevalo with Glendale police said two people were sleeping inside the home targeted when they heard the explosion just before 1 a.m.
This is the third explosion at this house which is near 66th and Olive avenues. The other two incidents occurred in June 2011 and July 2011, according to Arevalo.
Tom Mangan, a special agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives, said the pipe bomb was not elaborate.
"Simple will kill you just as easily when you look at the residence the vehicles house across the street you see how lethal these devices are," Mangan said.
Mangan said one of the homeowners works for the Deer Valley School District.
"It's puzzling to us why these homeowners are being targeted, why this specific individual is being targeted," he said.
Several neighbors described the homeowners as an average, older couple.
"(We're) lucky no one got hurt," Mangan said.
ATF and the FBI are working with Glendale police on this investigation. If suspects are caught, they could face state and federal criminal charges.
The homeowners have surveillance cameras installed around the house. Mangan would not say if they have any suspect(s) or person of interest(s).
"We'll get to the bottom of this soon," he said.