The 36-year-old man who fatally shot seven people and wounded 22 others in West Texas on Saturday purchased his weapon in a private person-to-person sale, allowing him to avoid a background check, according to multiple reports Tuesday.

The shooter, Seth Aaron Ator, was federally barred from possessing a firearm, ABC News reported. But in Texas, person-to-person sales do not require background checks.

Authorities say Ator used a rifle in a shooting spree in Odessa and Midland soon after being fired from his job. The rampage began after two Texas Department of Public Safety troopers pulled him over for a traffic violation and he shot and wounded one of the troopers. He then began driving around Midland and Odessa, randomly firing at people. At some point he ditched his car, fatally shot a 29-year-old U.S. Postal Service letter carrier and continued shooting people from the postal van.

Details of how the rifle was purchased came a day after Gov. Greg Abbott said the shooter previously failed a gun purchase background check, though Abbott didn't say why. A DPS spokesperson said Tuesday that the failed purchase happened in 2014, but didn't disclose a reason.

But the shooting — the fourth mass shooting in Texas in four years — prompted widespread calls for action from state leaders. Lt. Gov. Dan Patrick said Monday there should be a “strong look” at the lack of a required background checks for some private sales.

“And I believe as a supporter of the Second Amendment we should protect that family transfer or family sale, but any stranger to stranger — we don’t know how this person got the gun — but we do know that that’s a real loophole in the law, and I think the NRA [National Rifle Association] needs to get behind the president on that issue and really address that issue,” Patrick said.

In the aftermath of an El Paso shooting last month that left 22 dead, Abbott convened a commission of lawmakers, activists and law enforcement to discuss possible responses. The Texas Safety Commission held two meetings last month and Abbott has indicated that the group plans to issue a report with recommendations.

Abbott tweeted Monday night that “we’re working on a legislative package right now.” He didn't offer any details, however, other than that “expedited executions for mass murderers would be a nice addition.” On Tuesday, House Speaker Dennis Bonnen and Lt. Gov. Dan Patrick announced that they'd each form special legislative committees to find ways to prevent mass violence.

Matthew Watkins contributed reporting.