- Paul Anthony Ciancia, 23, is accused of opening fire at LAX
- He recently moved to Los Angeles from New Jersey, authorities say
- Ciancia sent "angry, rambling" texts to his brother and father, a source says
- The tone and nature of the messages raised concern, the source says
(CNN) -- The man who authorities believe opened fire inside a terminal at Los Angeles International Airport sent a series of "angry, rambling" text messages to family members in the days leading up to Friday's rampage, a source told CNN.
The revelation come as investigators are trying to piece together the background and possible motive of alleged gunman Paul Anthony Ciancia, who police say killed a TSA officer and wounded others in a shooting rampage inside Terminal 3 at LAX.
"We are currently investigating his background and more about him," FBI Special Agent in Charge David Bowdich told reporters.
Ciancia, 23, recently moved to Los Angeles from New Jersey. He appears to have lived in Delaware at one point. He graduated in 2008 from an all-boys Catholic school, the Salesianum School, in Wilmington, according to Brendan P. Kennealey, the school president.
It was not immediately clear how long he had been in Los Angeles or why he moved to the area.
How the LAX shooting unfolded In texts to his brother and father, Ciancia said he was unhappy and discouraged living in Los Angeles, according to the intelligence source with knowledge of the investigation. The source spoke on condition of anonymity, citing the ongoing investigation.
The tone and nature of text messages alarmed his family, the source said.
Search warrants were being executed at his residence in Los Angeles and his former residence in New Jersey, said a law enforcement official, who had been briefed on the investigation. The official, who spoke on condition anonymity, was not authorized to release details to the media.
According to LAX Police Chief Patrick Gannon, the suspected gunman carried a bag into the terminal, pulled "an assault rifle" out of the bag and opened fire.
Ciancia was shot several times in the chest by police, bringing to an end a shooting rampage that began about 9:20 a.m. just inside the doors of busy Terminal 3, where hundreds of passengers were clearing security and waiting to board flights.
Ciancia was taken to Ronald Reagan UCLA Medical Center, the intelligence source said.
In the aftermath of the shooting, investigators found information on the suspect expressing not just anti-federal government sentiment but also anger at the TSA specifically, according to a federal law enforcement official.
Eyewitnesses say the gunman asked "Hey, are you TSA?" If they answered "no," he moved on.
CNN's Joseph Netto and Paul Matadeen contributed to this report.
