The FBI is investigating the Austin, Texas incident as a potential act of terrorism

The gunman who killed two people and injured over a dozen in Texas may have been motivated by US strikes on Iran that killed the country's Supreme Leader and caused widespread civilian casualties, according to law enforcement sources cited by US media.

The attack occurred in a busy nightlife district in Austin near the University of Texas shortly before 2am on Sunday.

The suspect, identified as 53-year-old Ndiaga Diagne, opened fire outside Buford's Backyard Beer Garden, killing two people and injuring at least 14 others. The naturalized US citizen, originally from Senegal, drove past the venue several times before stopping and firing a pistol from his SUV at people gathered outside, according to Austin Police Chief Lisa Davis.

The attacker then exited the vehicle armed with a rifle and continued shooting at pedestrians before responding officers shot and killed him.

Photos released by the authorities show the suspect carrying a rifle and wearing a sweatshirt emblazoned with the words "Property of Allah." According to AP and Fox News sources, he also wore clothing displaying an Iranian flag.

A law enforcement source familiar with the investigation told the New York Post that the violence was "potentially an act of vengeance over the US attack on Iran." 

Alex Doran, the acting agent in charge of the FBI's San Antonio office, said the shooting was being investigated as a potential act of terrorism. "It's still too early to make a determination on that," Doran added.

The incident occurred a day after US and Israeli forces launched a large-scale strike on Iran, killing Supreme Leader Ayatollah Ali Khamenei, senior officials, and hundreds of civilians, including more than 100 children, according to Iranian authorities. Tehran has since retaliated with missile and drone strikes targeting US and Israeli military bases across the Middle East.

A Reuters/Ipsos poll published on Sunday found that only one in four Americans backed the strikes, with roughly half of respondents saying US President Donald Trump is too eager to use military force.

"Combat operations continue at this time in full force, and they will continue until all of our objectives are achieved," Trump declared in a Sunday evening address.