Last Updated at 3:38 p.m. ET
KILLEEN, Texas - An AWOL soldier told police he was "seeking retaliation" against the Army and indicated that he was planning attacks against the City of Killeen and Fort Hood, the same Texas Army post where 13 people were killed in a 2009 shooting rampage blamed on an Army psychiatrist, CBS News correspondent Bob Orr reports.
Killeen police arrested without incident 21-year-old Pfc. Nasser Jason Abdo on Wednesday after being alerted by "concerned citizens," and agents found firearms and "items that could be identified as bomb-making components, including gunpowder," in his motel room, said FBI spokesman Erik Vasys.
Federal charges are pending and will be filed, pending review of the prosecutor's office, Killeen Police Chief Dennis Baldwin said at a press conference. Baldwin said that it was a federal investigation, not a local police investigation.
U.S. law enforcement sources told Orr that a .40 caliber semi-automatic handgun, ammunition clips, more than 100 rounds of ammunition, a large quantity of smokeless gunpowder, batteries, clocks and a pressure cooker were found in Abdo's motel room.
There were indications that Abdo was dismantling shotgun shells to retrieve the gunpowder with the intention of using the pellets as shrapnel in explosive devices, Orr reports.
"Military personnel were a target of this suspect," Baldwin said. If he had not been stopped, "we might be having a very different press conference."
A law enforcement official told CBS News that Abdo had asked how to build explosives at a gun store near Fort Hood. His questions about explosives made the gun store worker suspicious and contact police, the official said. When police questioned Abdo at his motel, he made references to a plan to kill or injure people.
Gun store clerk Greg Ebert, a 17-year veteran of the Killeen police force who retired in 2010, said a customer arrived by taxi Tuesday at Guns Galore LLC, where the 2009 Fort Hood rampage suspect bought a pistol used in the attack. The customer bought 6 pounds of smokeless gunpowder, three boxes of shotgun ammunition and a magazine for a semi-automatic pistol, paying about $250.Ebert said he became concerned when the man asked questions indicating he didn't know much about the items, such as "What is smokeless powder?"
(At left, watch CBS News affiliate KWTX-TV from Waco, Texas, interview Ebert)
"(We) felt uncomfortable with his overall demeanor and the fact he didn't know what the hell he was buying," Ebert said. "I thought it prudent to contact the local authorities, which I did."
Killeen police did not immediately confirm Thursday whether the buyer was Abdo.
Two people associated with Abdo have been questioned but not arrested, the law enforcement official told CBS News.
Vasys said the FBI planned to charge Abdo with possessing bomb-making components later Thursday, at which time he would be transferred into federal custody. He said there was nothing to indicate Abdo was "working with others."
Abdo has been absent without leave from Fort Campbell, Ky., since the July 4 weekend.
"I would emphasize that any threat that Abdo posed is now over," Vasys said. "Suffice it to say we're looking into all aspects of Mr. Abdo's life to determine his motivations and intentions."
The Muslim American infantry soldier whose hometown the military lists as Garland, Texas, had applied for conscientious objector status last year, saying his religious beliefs would prohibit his service in any war. A military review board recommended this spring that he be separated from the Army.
The discharge was delayed after Abdo was charged with possessing child pornography. An Article 32 military hearing last month recommended Abdo for a court-martial. He has said he thought he was charged with a crime because he was seeking to leave the Army as a conscientious objector.
An Oklahoma attorney who has represented Abdo said Thursday he hasn't heard from Abdo in weeks and learned of the arrest from a Texas television station.
"I've been quite anxious to get in touch with him," said attorney James Branum.
Army psychiatrist Maj. Nidal Hasan faces a possible death sentence when he is tried next year on 13 counts of premeditated murder and 32 counts of attempted premeditated murder in the 2009 rampage at Fort Hood.
The Army post issued a statement seeking to reassure the community after Abdo's arrest Thursday.
"At this time, there has been no incident at Fort Hood," the statement said. "We continue our diligence in keeping our force protection at appropriate levels."
Fort Campbell spokesman Rick Rzepka referred all questions to the Pentagon.