Officers in Nassau County who had just buried a fallen colleague last week now have to brace for the funeral of another officer killed on the job.

Officer Arthur Lopez was killed Tuesday after getting shot in what had started out as a traffic stop. Ex-convict Darrell Fuller, 33, was arrested on charges of shooting him as well as another driver, 52-year-old Queens resident Raymond Facey, in a subsequent carjacking.

Fuller is set to be arraigned Thursday. He was being processed and it was not clear whether he had an attorney.

Lopez's death came the day after he and other officers attended the funeral of Nassau County highway patrolman Joseph Olivieri, who was killed last Thursday when he was hit by a car at a crash scene where he had responded.

On Wednesday afternoon, a somber police procession led Lopez's body from the county medical examiner's office to a West Babylon funeral home. Colleagues stood at attention as the hearse passed.

Bill Staker, who trained 29-year-old Lopez after he joined Nassau's elite Emergency Services Unit, called him the department's future and a young leader who always had a smile on his face.

"This whole thing, none of it makes sense," said Staker. 

The disbelief was also evident at Lopez's Babylon home, where mourners left flowers. Fellow officers carried out some of his personal effects, including his police dress uniform. 

"Emotions are running rampant all over the place right now," said PBA President James Carter. "It's a department that's in mourning, and it hasn't fully recovered from last week and now you get hit with this. A lot of the guys are hurting." 

Lt. Adam Scheiner said officers in the Emergency Services Unit were grieving "as a family who lost a brother."

Lopez was on patrol Tuesday in Bellerose Terrace, a community at the border of Queens and Nassau County. The officer and his partner spotted a damaged silver Honda that was "running on rims," suspecting it was wanted for leaving the scene of a hit-and-run accident, authorities said.

The officers gave chase, and the car pulled over. There was "a brief exchange of words" between Lopez and the driver before the driver left the vehicle and fired one round into Lopez's chest, police Chief Steven Skrynecki said, adding that the officer wasn't wearing a bulletproof vest.

The second officer administered first aid to Lopez, officials said. He was later hospitalized for trauma.

Lopez "lost his life to a cold-blooded killer," Nassau County Executive Edward Mangano said at a news conference.

The shooter got back into his car and drove away before abandoning the vehicle and accosting Facey, authorities said. He shot the Queens man in the head, dragged him out of his car and left him dead on the roadway as he drove away, they said. That car later was found abandoned in a residential neighborhood in Queens.

The slayings touched off a search for Fuller that included heavily armed NYPD officers going door-to-door in Queens. Authorities also closed the Cross Island Parkway for several hours, causing traffic delays.

A 911 caller reported hearing gunfire in Queens amid the massive manhunt for Fuller. Responding officers found him in a vehicle — not the one carjacked — with what appeared to be a self-inflicted gunshot wound.

He was taken to Jamaica Hospital, then transferred to Nassau County police headquarters Wednesday where officers were lined up outside.

"This suspect doesn't deserve to be on the same planet as Artie Lopez," said Scheiner. "Let justice be served and this person should never get out." 

Fuller had served five years in prison after pleading guilty to attempted murder in 2005, authorities said. He was jailed again in 2010 after violating his parole, but was released in May 2011.

Lopez lived on Long Island and was single. He joined the police force in 2004.

Nassau County Police Commissioner Thomas Dale announced Wednesday a new requirement for all on-duty officers to wear body armor while on field patrol, whether they're in uniform or plainclothes.

The funeral service for Lopez is scheduled for Saturday morning at St. Christopher's Church in Baldwin. 

A PBA-sanctioned memorial fund has been set up for Lopez. Donations may be made to the Police Officer Arthur Lopez Memorial Fund at 89 East Jericho Turnpike, Mineola, NY.