Police in Texas have killed two gunmen after they opened fire outside an event featuring cartoons of the Prophet Muhammad. What do we know about the men?
The duo arrived at the event in the same car and were wielding assault rifles before being shot and killed.
One of them, Elton Simpson, was once suspected of seeking to join militants in Somalia, but his Phoenix flatmate and accomplice Nadir Soofi was not known to authorities.
Dunston Simpson, his father, told ABC that his son, who worked at a dentist's office but had recently been absent, "made a bad choice".
Officials believe Simpson was the owner of a Twitter account that sent out several messages ahead of the attack.
The last tweet, sent just a few minutes before the attack, included the phrases "may Allah accept us as mujahideen" and "#TexasAttack".
Arizona court documents say Elton Simpson was born in the state of Illinois, then moved to Phoenix and converted to Islam.
He was convicted five years ago of lying to federal agents about plans to join an African terror group after travelling to the continent.
A grand jury alleged he lied to FBI agents when he told them he had not discussed travelling to Somalia to engage in "violent jihad".
The documents show that he was found guilty of one count of making a false statement on 14 March 2011 and was sentenced to three years of probation.
Speaking to ABC, Kristina Sitton, one of Simpson's lawyers in the 2010 trial, said she saw him as "harmless".
"He grew up the most normal guy. Just a normal high school guy," she said. "Converting to Islam seemed like a good thing for him."
Simpson never struck her as someone who would do this sort of thing, she said.
"I'm not a bleeding heart, I'm a Republican. I've seen some pretty bad guys and he seemed pretty normal."
According to local media in Dallas, Soofi was born in Garland, Texas, to a Pakistani father and American mother.
At the time of the attack in his home city, he shared an apartment in Phoenix with Elton Simpson from where he ran a carpet cleaning business, the authorities say.
He is reported to have been arrested on numerous occasions for minor offences including dangerous driving and unlawful possession of drugs.
His mother Sharon Soofi said he was "politically involved" - especially in matters relating to the Middle East - but there was no indication he would get involved in violence.
"I don't know if something snapped [at the time of the attack] or if Elton Simpson was just working on him," his mother Sharon Soofi said.
Soofi's maternal grandmother told NBC News that he had been "influenced by extremists" and was talked into carrying out the attack.
Shirley Dromgoole said that that her divorced 34-year-old grandson, who leaves an eight-year-old son behind, "was a good boy every time I saw him".
She said Soofi was brought up as a Muslim by his father - and when his parents divorced he and his brother moved to Pakistan to live with their father and stepmother, a source told CNN.
In the 1990s, Soofi was educated for a while with his brother in Islamabad but is reported to have left abruptly to go and live with his mother again in the US.
A law enforcement official told CNN that unlike Simpson, who had been convicted of a terror-related charges, Soofi was relatively unknown to federal investigators.
The authorities had no idea that the pair planned to launch Sunday's attack, officials said.
Soofi is reported to have dropped out of his medicine course at the University of Utah in 2003 and from then onwards began to make increasingly outspoken comments on social media.
On his Facebook page he is reported to have expressed admiration for various outspoken or hardline Islamic figures - but nowhere on it did he condone the use of violence.