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Master Sgt. Debra Clayton, 42, died Monday morning at Orlando Regional Medical Center after Markeith Loyd shot her three times outside a Pine Hills-area Walmart, police said.

“We’re not going anywhere. If we don’t have this individual by nightfall, we are not going anywhere,” said Orlando police Chief John Mina.

That sentiment still rang true as the search reached its 11th hour.

>> WFTV.com live blog: Manhunt underway for Markeith Loyd

Authorities are offering a $60,000 reward for information on the whereabouts of Loyd.

"We're going to bring this dirtbag to justice and he's going to jail," Mina said.

Dozens of police vehicles descended on the area around the intersection of Pine Hills Road and North Lane, just south of Royal Oaks and Pineview apartments.

"We have searched dozens of apartments and residences in an effort to find the suspect and bring him in. We have deployed numerous officers and detectives who specialize in looking for suspects who try and avoid capture. We are using every resource possible to find him and arrest him," Mina said.

But by nightfall, only a few police cruisers remained outside a lone apartment in a complex that had been swarming with SWAT team members looking for Loyd.

Mina said law enforcement believes that Loyd has been receiving help to stay hidden from officers.

Law enforcement officials warned that anyone helping Loyd hide could face serious charges.

“I am confident we will find him. I can tell you that it doesn’t matter where he is, we will track him down to the ends of the earth. Trust me on that,“ Mina said.

A witness to the shooting said the gunman was wearing a shirt that read "security," but Mina said Loyd was not a security guard.

"(The shooter) was an average looking dude, he walked by me, had a security vest and everything," witness James Herman told WFTV. "I was walking down the sidewalk, right past the officer, and I heard her tell him to stop, or whatever, and he shot her. He shot her down. He took off running. It's unreal."

Herman said the man continued to shoot behind him as he was running from the scene.

"As he was running, he was shooting back, he was shooting backwards," Herman said. "I hit the ground on the side over here because I wasn't sure where the shooting was coming from at first.”

Clayton was outside the Walmart when she was approached by a shopper, Herman said.

"The customer walked up to her and said that someone they were looking for, wanted, was in the store in the line to check out," he said. "She went in there, I guess, to confront him. As she was going back to Walmart, he was coming out, and he shot her."

An Orange County sheriff's deputy spotted Loyd at the intersection of North Lane and Pine Hills Drive and followed him to a nearby apartment complex, officials said.

He opened fire on the deputy, hitting the deputy's unmarked SUV twice, and then carjacked a second vehicle and continued to flee, the Orange County Sheriff's Office said.

He abandoned the vehicle near the intersection of Rosemont Avenue and Cinderlane Parkway and ran, deputies said.

"We have a lot of police resources trying to catch the suspect," Mina said. "Local, state and federal authorities are all working together diligently to bring him to justice, and he will be brought to justice, I can assure the community of that."

Orange County Sheriff Jerry Demings said he had known Clayton for many years and was devastated by her killing.

"She is someone I know very well," Demings said. "In fact, I hired her when I was the OPD chief. My heart goes out to her family, the OPD and the city of Orlando as we deal with these circumstances."

Clayton, a 17-year veteran of the force and mother of two, was carried from Orlando Regional Medical Center in a flag-draped coffin and was driven from the hospital, accompanied by a police escort.

Authorities said Loyd was also wanted in connection with the shooting death of his pregnant ex-girlfriend, Sade Dixon. He has been on the run since Dec. 13, when Dixon, 24, was shot to death outside her home in the 6000 block of Long Peak Drive.

Orlando Mayor Buddy Dyer declared Monday a day of mourning in memory of Clayton and senior Orange County Sheriff's Office motorcycle Deputy Norm Lewis, who died in a crash while searching for Loyd.

>> Related: Deputy struck by car, killed during search for suspected police killer

"As in the past, I'd like to call on our entire community to stand united in support of all of the families of both the deceased and the injured," Dyer said. "But as the sheriff and the chief have done, I am also calling on the community to provide any information that will lead to the capture of this violent criminal."

“Our thoughts and prayers are with the family and friends of the two Orlando-area police officers killed in the line of duty today. The brave men and women who serve in our nation’s law enforcement community put their lives on the line every day to keep us all safe. We owe them an enormous debt of gratitude for their service and we join them as they mourn the loss of their colleagues,” said Sen. Bill Nelson.

Clayton was one of the first officers to respond to the Pulse nightclub massacre on June 12, according to police records.

"Debra Clayton is a hero and she gave her life protecting the community that she loves. She will be deeply missed," said Mina.

Rep. Val Demings said she "had the honor of working with Sgt. Debra Clayton for many years at the Orlando Police Department."

“Sgt. Clayton was a fine law enforcement officer, wife, and mother who served her community with pride and as a mentor to young women,” Demings said. “Gone, but never forgotten.”

Commissioner Regina Hill said Clayton was "a beautiful person."

Clayton and Lewis were University of Central Florida alumni.

“Master Sgt. Clayton and Deputy First Class Lewis dedicated their lives to making our community safer, and they were outstanding role models,” UCF President John Hitt said. “Our UCF family joins the Orlando Police Department and Orange County Sheriff’s Office in mourning their deaths. They are heroes and Knights forever.”

Loyd, a convicted felon, has been arrested in Orange County 20 times since 1994, court records said.

Anyone with information is asked to call Crimeline at 1-800-423-TIPS (8477).