A gang member used armor piercing-bullets and an AR-15 to kill two Palm Springs police officers in a planned "ambush" on Saturday, said Riverside County District Attorney Mike Hestrin in a press conference Wednesday.

John Felix, 26, shot an assault rifle through the front door of his house, killing Officers Jose "Gil" Vega and Lesley Zerebny and wounding a third officer – all of whom were wearing bulletproof vests. Felix was captured early Sunday morning after a 12-hour standoff with police and SWAT teams.

Felix has been charged with two counts of first-degree murder and three counts of attempted murder, with enhancement filed on each charge for the use of body armor and armor-piercing bullets. Felix was also charged with illegal possession of an assault weapon and possession of a stolen firearm. Hestrin said Felix attempted to murder three other officers beyond the two who died by shooting directly at them. One of them was injured and was released from the hospital Sunday.

Felix’s weapon was an AR-15 rifle with a scratched-off serial number, according to the DA's office. This kind of rifle can be legally owned in California, but not by Felix, who was already a convicted felon. Felix also possessed several illegal high-capacity magazines.

"This individual wanted to kill police officers," Hestrin said, referring to Felix. "That's the motive. He wanted to gun down police officers because they wore the uniform."

Hestrin described the events as a targeted "ambush."

"These police officers walked into a trap," he said.

The Palm Springs shooting now joins a growing list of fatal police ambushes, including killings in Dallas and Louisiana, where gunmen have intentionally targeted law enforcement. On-duty police deaths have been declining in recent years, but ambushes – the rare cases that cops fear the most – are rising.

At least 18 police officers have died in ambushes so far in 2016, according to stats kept by the National Law Enforcement Officer’s Memorial Fund. That is the most of any year since at least 1997, FBI records show.

Hestrin would not clarify if the armor-piercing rounds pierced the officers' bulletproof vests. Standard ammunition might have been stopped by the officers' bulletproof vests, making the difference between life and death.

"He armed himself with a dangerous weapon, an assault weapon, and he used very lethal ammunition, and it had an effect on what happened," he said.

Felix is eligible for the death penalty. Hestrin said his office will decide whether or not to seek it within the next three weeks.

"We want to know everything about this individual," he said. "We're not ready to make that decision."

Hestrin said the death penalty process involves talking to the family members of the victims and considering their desires. Officer Zerebny's father, David Kling, told The Desert Sun on Tuesday he hopes the DA seeks the death penalty.

Hestrin's father is a former Palm Springs police officer. "I'm heartbroken like everybody in law enforcement."

Felix's arraignment will take place tomorrow at 1:30 p.m. in Indio, where the charges were filed.

The 12-hour standoff ended early Sunday morning when a SWAT team used tear gas to force Felix out of his barricaded house, pelting him with non-lethal rounds until he surrendered. Felix was wearing a bulletproof vest and carrying the high-capacity magazines – but did not have a firearm on him – when he was taken into custody.

The events of the tragic shooting began Saturday afternoon, when a neighbor called 911 to report that Felix was arguing with family members. Four officers responded to the scene, then approached the front of the home and spoke to Felix through a metal screen door. When they told Felix to step outside, he opened fire without warning.

Vega, a 35-year veteran of the force with eight children, was two months from retirement. He was working extra hours outside of his normal shift when the shooting took place Saturday. Zerebny had recently returned from maternity leave after giving birth to a baby girl who is now four months old. A memorial service for both officers is scheduled for Tuesday at 11 a.m. at the Palm Springs Convention Center. Between 10,000 and 15,000 guests are expected to attend.

Felix is a known member of the Varrio Las Palmas gang, which claims as its turf the Golden Sands Mobile Home Park – two blocks north of where the two officers were killed on Saturday.

Felix was previously sentenced to four years in prison in a 2009 attempted murder case after he pleaded down to assault with a firearm. He served only 18 months and was released in October 2011. He was discharged from parole in May 2015.

Hestrin said he would not release any details of the incident that could jeopardize the trial.