"We are assuming that Kara was abducted at gunpoint and is being held hostage," said Lititz Borough police Chief William Seace. "Mr. Ludwig is armed and considered dangerous."

Ludwig allegedly shot Kara's parents, Michael F. and Cathryn Lee Borden, both 50, after they questioned him about staying out all night with their daughter. Both were shot one time in the head.

The Bordens summoned Ludwig to their suburban home at 15 Royal Drive, Warwick Township, home shortly before 8 a.m. Sunday. Ludwig had dropped Kara off at the home earlier that morning, according to police.

When Ludwig returned to the home, he carried a duffle bag containing rifles, handguns and knives. He concealed a handgun in his clothing before entering the home, police said.

The discussion between Ludwig and the Bordens became heated. As Michael Borden escorted Ludwig to the front door, Ludwig pulled out the gun and shot Borden, police said.

Kara's brother, David, 9, and sister Katelyn, 15, also were inside the house.

Katelyn told police she watched Ludwig shoot her father. She hid in a bathroom while Ludwig allegedly killed her mother.

After hearing the second gunshot, Katelyn told police that Ludwig yelled for Kara.

Police said the couple fled the house and drove away in Ludwig's red 1998 Volkswagen Jetta TDI. The registration plate is EHH0994.

Katelyn and David also fled the house and asked neighbors to call 911 at 7:58 a.m.

"The boy found a neighbor and told them 'Mommy and Daddy had been shot,'"ˆ" Seace said. "Nobody had any idea if (Ludwig and Kara) were still inside the house."

Warwick Township police Sgt. Richard Groff and Officer Samuel DaBella, along with Lititz Borough police Sgt. Kerry Good, were the first to arrive.

Groff found Katelyn outside a neighbor's house.

Police surrounded 15 Royal Drive but did not know if Ludwig was still inside. They waited about two hours for Lancaster County Special Emergency Response Team officers to arrive.

Tear gas and a concussion grenade were fired into the house before the SERT officers stormed inside.

The officers discovered the two bodies, but Ludwig and Kara Borden were gone.

"They got about a two-hour head start on us," Seace said.

Police also searched Ludwig's home at 422 W. Orange St., Warwick Township, where he lives with his father, Gregory P. Ludwig, 54. Firearms and gun cases were found inside the house.

Investigators confiscated computers from the Royal Drive and West Orange Street homes to look for e-mails exchanged between Ludwig and Kara.

Warwick Township police issued the AMBER Alert about noon Sunday.

The alert system, which stands for America's Missing: Broadcast Emergency Response, links police departments with broadcasters to notify the public to be on the lookout for abducted children.

Kara is described as 5-foot-1-inch tall and weighing about 100 pounds. She has brown hair with blond highlights and was last seen wearing a black sweat shirt emblazoned with the name of Pillar, a Christian rock band.

Reports about the abduction were broadcast on Internet, radio and television stations along the East Coast. A description of the Volkswagen and its registration plate were displayed on interstate highways.

Police received more than 100 tips from the public in the first 10 hours.

"The public response has been overwhelming," Seace said. "Every tip is being followed up on."

Gregory Ludwig told police that his son could have fled to a family-owned cabin in Juniata County. State police checked the cabin but did not find Ludwig or Kara.

The only area police could confirm that the couple traveled through was Clay Township, after a cell phone belonging to Kara was found along a road.

Warwick Township police Chief Richard F. Garipoli Jr. and Lancaster County District Attorney Donald Totaro were supervising a team of investigators from police departments across the county. The FBI, U.S. Marshals and Pennsylvania State Police also are searching for the couple.

The Bordens moved to Warwick Township from North Carolina in 1996 or 1997, according to neighbors. Mr. Borden worked at Science Press Division, a printing company at 300 W. Chestnut St. in Ephrata.

According to neighbors, the Bordens also have two older sons: James, who attends graduate school in Chicago, and Justin, who is in the military and served in Iraq.

Intell reporter Aileen Humphreys contributed to this story.