The U.S. Attorneys' office is using a successful guilty plea in a Washington, D.C., shooting case to press for more regulations on high-capacity gun magazines.

On Wednesday, a Virginia man pleaded guilty to three felonies, including a terrorism charge, for shooting a security guard at the Family Research Council (FRC) in downtown Washington last year.

U.S. Attorney Ronald Machen said the attack, which was motivated by the group’s opposition to same-sex marriage, was evidence that the government should limit the number of bullets a weapon can hold.

“This case highlights the dangers of access to high-capacity magazines that allow killers to inflict carnage on a mass scale in the blink of an eye,” Machen said in a statement following the guilty plea.

Obama and many Democrats have been pushing to limit the capacity of magazines to 10 rounds, arguing that it could help reduce the number of people a gunman could shoot in a mass attack.

According to the Justice Department, Floyd Lee Corkins approached an unarmed security guard at the conservative Christian group’s Washington headquarters on Aug. 15. Corkins pulled a semi-automatic 9mm pistol from his backpack, shot three times and struck the arm of the guard, who managed to wrestle the firearm away from Corkins, according to the DOJ.

Following Corkins’s detainment, police officers found two fully loaded 9mm magazines and 50 additional rounds of ammunition in his pockets and backpack. Corkins had legally purchased the gun from a Virginia store one week earlier, according to court records.

The size of the magazine Corkins used in the shooting was not revealed in court documents, but according to Corkins's statement of offense, the two additional magazines that officers found in his pockets each had 15 rounds in them.

Corkins told FBI investigators later that he was planning to go to a second organization, also known for its opposition to same-sex marriage, and carry out a similar shooting attack, but the injured guard stopped him.

Corkins was also carrying 15 sandwiches from Chick-fil-A in his backpack, which he said he wanted to smear on the faces of the people he intended to kill that day. A self-proclaimed political activist, Corkins told investigators: “Chick-fil-A came out against gay marriage so I was going to use that as a statement.”

Corkins pleaded guilty to charges that he committed an act of terrorism while armed, an assault with intent to kill while armed, and the transportation of a gun and ammunition across state lines.

“Were it not for the heroic guard who tackled Floyd Corkins, he could have succeeded in perpetrating a mass killing spree in the nation’s capital,” Machen said.

“Today’s guilty plea makes clear that using violence to terrorize political opponents will not be tolerated.”

The shooting ignited a flurry of accusations lobbed between both sides of the same-sex marriage debate.

In 2010, the Southern Poverty Law Center (SPLC) placed the FRC on its list of hate groups for its statements about the gay community.

In the wake of the shooting, the National Organization for Marriage, one of the nation’s leading opponents of same-sex marriage, said the shooting was a direct result of the SPLC’s decision.

The SPLC vehemently denounced the shooting and rejected the use of the violence, but it stood by its categorization of the group, which has promoted the idea that a homosexual lifestyle is linked to pedophilia.

Wednesday’s guilty plea is the first time the government has charged someone with violating the District of Columbia’s Anti-Terrorism Act of 2002, which qualifies a person’s terrorist intent as an attempt to “intimidate or coerce a significant portion of the civilian population of the District of Columbia or the United States.”

Corkins’s sentencing is set for April 29. The terrorism and assault charges each carry a maximum penalty of 30 years in prison, while the weapons-related charge carries up to 10 years in prison.

--This report was last updated at 5:41 p.m.