The 21-year-old Texan accused of gunning down 22 people in the El Paso Walmart massacre pleaded not guilty to capital murder during his arraignment on Thursday.

Around 80 members of the public crammed into the El Paso County Courthouse to witness the first appearance of Patrick Crusius, who authorities say admitted to targeting Mexicans in the Aug. 3 mass shooting.

Some wiped away tears as Crusius, dressed in a dark suit and glasses, entered his plea.

Local prosecutors have said they will seek the death penalty.

The Department of Justice called the shooting an act of domestic terrorism and feds are weighing capital murder and hate crime charges.

Crusius is accused of driving 11 hours from his hometown of Allen, near Dallas, to El Paso and using an AK-style assault rifle in the slaughter that left another 26 injured.

He turned himself in less than an hour after the bloodbath, telling cops, “I’m the shooter,” according to his arrest warrant.

Prosecutors on Sept. 27 shared evidence with the defense, including police and FBI interviews of Crusius, his cellphone data, school records and tens of hours of Walmart security camera footage from the time of the shooting.

It also includes the FBI’s “manifesto analysis” of the racist screed authorities say Crusius posted online minutes before the attack, saying the shooting was “a response to the Hispanic invasion of Texas.”

About 2,000 people were at the scene of the massacre, so nearly all of the city’s 700,000 residents knew somebody affected by the shooting.

The first judge in the case recused herself because she knew one of the victims. The lead prosecutor’s sister was in the Walmart during the attack, and said the gunman walked right past her.

Crusius is being held without bond at the El Paso jail, where he’s been on suicide watch and separated from other prisoners since his arrest.

With Post wires