Police Commander Ronald Saunier said the suspects went to Fero's Bar & Grill bar to rob it before closing time Wednesday, but he didn't go into details about how it turned into a murder case.
"It appears that the motive of this crime was robbery, that they came in there, I don't want to say that it was a robbery gone bad, but it wound up being a robbery. The arson was set to try to cover up the crime scene," he said.
An officer on routine patrol around 2 a.m. Wednesday noticed a fire at the bar. Inside, firefighters found the bodies of one man and four women, including 63-year-old Young Fero, the bar owner. Investigators think the fire had been burning for about 15 to 20 minutes before the officer spotted it.
Joseph Hill, 27, and his brother, Lynell Hill, 24, and Dexter Lewis, 22, were all arrested in Denver starting late Wednesday night, police said.
Investigators were led to the trio because of some tips that came in after a news conference that afternoon. Detectives also had help from the Bureau of Alcohol, Tobacco and Firearms and the U.S. Marshals Service's fugitive unit. Saunier said he believes the suspects had been to the bar before.
The Denver medical examiner identified the other victims as Daria M. Pohl, 22; Kellene Fallon, 45; Ross Richter, 29; and Tereasa Beesley, 45. Pohl, Fallon and Beesley were from Denver. Richter's hometown wasn't released.
The medical examiner didn't release the cause of death. Police haven't said how they died and wouldn't discuss whether any weapons were found.
The suspects are being held on suspicion of first-degree murder, felony murder, aggravated robbery and arson.
The bar is in a strip mall about five miles south of downtown Denver, just beyond the upscale Cherry Creek North shopping district. It is wedged among a check-cashing store, a tennis shop, a nail salon and a car repair business on busy Colorado Boulevard.
Police said the fire did extensive damage, but little of that was visible from the outside.
The bar attracted both regulars and people staying in nearby hotels, but neighbors said it didn't seem busy most days.
Frequent patron Chris Brady said the bar's customers ranged from "semi-homeless-looking people" to patrons in suits and ties.
He was at the bar for a regular poker game held Tuesdays and left at about 11 p.m.
"There was nobody random or crazy in there," Brady said.
Brady said Fero was known for cooking up beef dishes for customers at a moment's notice and usually would close the bar herself.
She bid him goodnight Tuesday as he paid his tab.
"She said, "Thank you, sweetie. Have a good night,'" Brady said. "I said, 'You too.'"
Mike Spinale, one of Fero's neighbors in Aurora, described her as "really nice."
"She didn't speak much, but I know she owned a bar and she worked all the time," Spinale said. "She told me she did everything herself."
Danny Fero, who said he was Young Fero's ex-husband, said he talked with Young Fero about a month ago regarding a visit with their daughter, but she made no mention of any threats. He said he was shocked by the events at the bar he once co-owned with her.
He told The Denver Post the two had met when he was working as a spokesman and photographer for the U.S. Army in Seoul, South Korea, and she was a clerk at the Korean Ministry of Agriculture. The two later married and had a daughter.
Jerry Richardson, who maintained an ATM at the bar, described Young Fero as "feisty."
"When she wanted that machine fixed, she would tell you about it," Richardson said.
Few details were immediately known about the other victims.
At an address listed for Pohl, a man who answered the door declined to comment. But neighbors Bert and Suzanne Kasben expressed disbelief that the studious 22-year-old was killed.
"She was always working," Bert said, adding he knew she held several waitressing jobs.
The Kasbens said Pohl was one of three sisters in a tight-knit family who often were seen walking their dog in a quiet cul-de-sac.
Meanwhile, Beesley was listed in state records as the owner of Maxim Lounge, another Denver bar.
Frank Peluso, who works in an office building half a block from Fero's Bar & Grill, said he used to eat lunch at the establishment but hasn't been there in three years. It seemed to be declining and the owners have tried various things to attract more business, including offering karaoke, he said.
"It's one of those places that you wonder how it stays in business," Peluso said.
Resident Matthew Neam said you can't see into the bar because the front windows are frosted. He said he and his friend used to joke about what might be inside.
"I've never gone in there," Neam said. "It always looked kind of sketchy to me."
Associated Press researcher Rhonda Shafner in New York and AP writer Nicholas Riccardi in Denver contributed to this report.