(CNN) — A gunman in central Florida killed a woman Wednesday, returned to the scene and killed a TV journalist covering that death, and then fatally shot a 9-year-old girl nearby before he was arrested, authorities said — shootings that have left investigators scrambling to determine a motive.

The suspect — also accused of injuring the girl’s mother and one of the journalist’s colleagues — was taken into custody Wednesday afternoon, a sheriff’s office said, ending a spate of violence that stretched across several hours in a neighborhood just west of Orlando.

“No one in our community — not a mother, not a 9-year-old, (and) certainly not news professionals — should become the victim of gun violence in our community,” Orange County Sheriff John Mina said in a news conference detailing the suspect’s arrest.

“We really don’t know what was in the mind of this suspect,” Mina said. “Hopefully at some point that he’ll talk to us about what his motives were.”

The suspect, Keith Melvin Moses, 19, is being held on a murder charge in Wednesday’s first shooting, and is expected to be charged in the others, Mina said.

The first shooting, reported around 11 a.m. Wednesday, killed a woman in her 20s inside a vehicle on Hialeah Street in Orange County. That woman is believed to be an acquaintance of the suspect, Mina said.

Later in the day, after the vehicle had been towed, the gunman returned to the area and shot two Spectrum News 13 journalists — a reporter and a photographer — who were covering the woman’s killing, Mina said.

One of the journalists died. The other was in critical condition Wednesday, but was speaking and was expected to go through more treatments at a hospital Wednesday night, the news station said, without naming either.

After the journalists were shot, the suspect then entered a home on a nearby street and shot a mother and her 9-year-old daughter, the sheriff said. They were both taken to a hospital, where the child died and the mother was in critical condition Wednesday evening, authorities said.

“We don’t know why he entered that home,” the sheriff said.

Investigators also are looking into whether the suspect knew that the Spectrum News 13 employees were members of the media.

Officials said they believe Moses had no connection to the journalists or the mother and her daughter.

The names of those killed and injured were not released by authorities Wednesday.

‘Every reporter’s absolutely worst nightmare’

Investigators had quickly identified Moses as a suspect in the first shooting and were following leads when the TV journalists were shot around 4 p.m., the sheriff said.

The two journalists were shot in or around their vehicle, Mina said.

“That vehicle was almost exactly in the same spot as the vehicle was from the homicide this morning,” Mina said. “It’s unclear why exactly they were targeted.”

The journalists’ vehicle “didn’t look like a typical news vehicle with a lot of markings on it,” Mina said.

Spectrum News 13, a CNN affiliate, mourned their slain colleague during a newscast Wednesday. It said it wasn’t yet naming the two employees.

“These are people that this afternoon we were having regular conversations here in the newsroom. It was a regular day. And truly not just colleagues, but family members,” anchor Greg Angel said.

Spectrum News 13 also thanked employees of competing news outlets for rushing to their colleagues’ aid.

“Some of our competitors … rushed to the aid of our colleagues, and we want them to know how much we appreciate them,” anchor Tammie Fields said. “Because when danger was happening, they could have run the other way. But apparently they ran right over to our crews and helped.”

Luana Munoz, a reporter for CNN affiliate WESH in Orlando, described an emotional scene after her fellow journalist died. Her colleagues had left the crime scene on Hialeah Street moments before the shooting, according to the station.

“This is every reporter’s absolutely worst nightmare. We go home at night afraid that something like this will occur and that is what happened here,” Munoz said. “We have learned that a fellow reporter has died while covering a shooting.”

“There are members of his family here, along with his fiancée, who are incredibly distraught tonight,” Munoz said. “There are other media people who are corralled together and standing in solidarity tonight as one of our own has passed.”

Spectrum News 13’s parent company, Charter Communications, released a statement following the attack.

“We are deeply saddened by the loss of our colleague and the other lives senselessly taken today,” the statement reads. “Our thoughts are with our employee’s family, friends and co-workers during this very difficult time. We remain hopeful that our other colleague who was injured makes a full recovery. This is a terrible tragedy for the Orlando community.”

In a statement, CNN called the shooting “an absolute tragedy” and noted that the organization “stands with our affiliate partner, Spectrum News 13, and will support them and the families of these journalists in any way we can.”

White House Press Secretary Karine Jean-Pierre also released a statement, saying, “Our hearts go out to the family of the journalist killed today and the crew member injured in Orange County, Florida, as well as the whole Spectrum News team.”

Suspect armed with handgun when arrested, sheriff says

The suspect was arrested near the area of the shootings, Mina said.

Investigators took from him a handgun, “which we believe we’re linking to these cases as well,” the sheriff said.

“The suspect is not saying much right now,” Mina said.

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