(NBC) --- As law enforcement officials sought to piece together the motive for an armed assault Friday at Los Angeles International Airport, a leading organization that tracks U.S. hate groups and extremist organizations reported Saturday that the suspected gunman may have been influenced by propaganda of the antigovernment "patriot" movement and fringe conspiracy theories.

As reported Friday by NBC News, the suspect, identified by authorities as 23-year-old Los Angeles resident Paul Anthony Ciancia, was carrying anti-government literature outlining an alleged conspiracy to create a single global government when he opened fire on workers with the Transportation Safety Administration, killing one and injuring several others.

But a blog post by Mark Potok, an expert on U.S. hate groups with the Southern Poverty Law Center, added new details about what he described as a one-page "manifesto" that included references to the Federal Reserve and "fiat currency."

Citing a knowledgeable source with ranking law enforcement contacts, Potok said Ciancia also had a note containing derogatory comments about former Department of Homeland Security Secretary Janet Napolitano.

"Ciancia's language and references seemed to put him squarely in the conspiracy-minded world of the antigovernment ‘Patriot' movement," Potok wrote. "The New World Order refers to a longstanding conspiracy theory that today, in its most popular iteration, claims that global elites are plotting to form a socialistic 'one-world government' that would crush American freedoms. Often, the root of the alleged conspiracy is traced to the 1913 creation of the Federal Reserve and the adoption of fiat currency — paper money that is not backed by gold, as it was once was in the U.S."

People associated with the patriot movement "see the DHS … as an enemy and even a collaborator in the New World Order conspiracy," he added. The TSA is an agency of the DHS.

Authorities have not indicated whether they have determined a motive for the attack on Friday allegedly authored by Ciancia, who lived in southern New Jersey before moving to California.

Ciancia is also accused of wounding two other TSA workers in the shooting Friday morning at one of the busiest airports in the country. Several other travelers were injured as they fled.

Authorities said the gunman entered the secure area of the airport through a gateway normally used by travelers exiting the terminal, pulled out a semi-automatic rifle and opened fire on unarmed TSA workers at a checkpoint.

Still firing, he continued walking through Terminal 3 of the airport, where police shot him several times in the chest. He was taken into custody in critical condition.

The TSA confirmed the identity of the slain officer as 39-year-old Gerardo I. Hernandez, according to an agency official. Hernandez is the first officer to have been killed in the line of duty in the agency's 12-year history.

Law enforcement officials say the crime scene is extensive and authorities are investigating the suspect's background. The airport said on its official Twitter feed that it had no timetable for when the FBI would complete its investigation of the horrific incident.

Ciancia had sent a suicidal text message to his brother before the shooting and was carrying anti-government material critical of the federal government and the TSA, police said Friday.

FBI agents armed with a search warrant scoured Ciancia's home in the L.A. area late Friday, FBI spokeswoman Laura Eimiller told Reuters.

Federal officials told NBC News it was unclear whether the gunman was targeting the TSA workers or was trying to shoot his way farther into the airport. But a witness said the shooter, calmly walking through the terminal with his weapon, approached him with a one-word question.

"All he said was, 'TSA?' Just like that," Leon Saryan told MSNBC.

The shooting started about 9:20 a.m. (12:20 p.m. ET) at Terminal 3, which serves Virgin America and other airlines.

Los Angeles Mayor Eric Garcetti said at a news conference Friday that the suspect had "more than 100 more rounds that could've literally killed everybody in that terminal today."

When the gunfire erupted, travelers who were waiting to snake through the security line abandoned suitcases and hit the ground.

"We were just standing there in line, and somebody started shooting," said Nick Pugh, a witness, who told NBC Los Angeles that he heard eight to 10 shots. "Everyone dropped to the floor and started crawling along the ground."

The airport said that seven people were injured in all but that the nature of all injuries wasn't clear.

The shooting brought one of the nation's busiest airports to a standstill.

The Federal Aviation Administration grounded flights at LAX, where 1,500 flights take off and land every day. Passengers heading there for departing flights were stuck in colossal traffic jams. Some abandoned their rides and rolled their suitcases the last distance to the airport.

According to the LAX official Twitter account, 724 scheduled arriving flights were affected, with an estimated 67,850 passengers impacted, while some 826 scheduled departure flights were affected, with an estimated 99,200 passengers impacted.

The rest of the flights were held on the ground in Los Angeles or at their originating airports, said Gina Marie Lindsey, executive director of Los Angeles World Airports. The ground stop applied to airports roughly west of and including Denver, officials said. It was imposed shortly after the shooting began and was lifted at 3 p.m. (6 p.m. ET).

"This has been a trying day for everyone, I know," Lindsey said.

Passengers who left behind luggage and other belongings in Terminal 3 as they fled the hail of bullets will be permitted to collect their property beginning at 10 a.m. (1 p.m. ET) Saturday, the airport tweeted. Affected passengers are instructed to go to their respective airline ticket counters.

Multiple airlines — including Virgin America and Spirit Airlines — warned of delays and cancellations amid the fallout. Frontier Airlines, meanwhile, announced it would operate via Terminal 2 on Saturday, Reuters reported.

President Barack Obama was briefed on the shooting, the White House said in a statement. Obama called TSA Administrator John Pistole to express his condolences to the family and friends of those injured, including the TSA employee who was killed in the line of duty, a White House official said.

In 2002, an Egyptian national opened fire at the El Al ticket counter at LAX, killing two Israelis before he was shot dead. Authorities ruled it a terrorist incident, even though the shooter was not tied to a known group.