Police say they believe that home invasions by armed men this week in Pearl City and St. Louis Heights are connected and are not random acts of violence.

Under reporters' questioning, the Honolulu Police Department's spokesman, Major Frank Fujii, refused to say if the robberies were connected to drugs, gambling or gangs.

"We believe we have identified the motive for these home invasions but we won't go into any more detail than that," Fujii said. "What we do want residents to know is that we don't believe these are random acts against citizens. The suspects in the St. Louis Heights case are the same as in the homicide robbery that occurred in the Pearl City area the night before."

No arrests have been made.

In the St. Louis Heights robbery at 11 p.m. Monday, victims told police there was a knock at the door. When they answered, three men burst in armed with at least one assault rifle and ordered all 10 people in the house to lay on the ground.

Police were told the men asked about a former tenant and demanded drugs from the current residents, striking two victims with the butt of the rifle and causing minor injuries.

When they didn't find the former tenant they robbed the victims of cell phones, wallets and other items before leaving, police said.

The descriptions of the suspects in that robbery matched the descriptions of suspects in a robbery after midnight Sunday in Pearl City in which a man was killed.

In each case two of the suspects wore black, hooded shirts with black pants; were black men; and were believed to be in their early to mid-20s. In the Pearl City homicide, the two suspects wore white goalie masks. At the home on Oswald Street in St. Louis Heights, two of the three suspects covered their faces with dark bandannas.

Asked if the police have evidence other than the suspects' appearance to link the two crimes, Fujii replied, "I can't say for sure."

There was no forced entry in the Pearl City case, police said. Police and witnesses said the suspects entered the home, stabbed and dragged Brendan Caires, 27, outside and also struck Caires' 27-year-old girlfriend in the head with the butt of a handgun.

Alfred Caires told The Advertiser on Monday that the suspects demanded things from his son, an argument ensued and Brendan Caires was stabbed once in the chest. He died at a hospital.

"They came into the house and stabbed my son and dragged him out into the yard," Alfred Caires said. "I have no idea why they did it."

Fujii said these robbers are dangerous men, but he said they are not likely a threat to the general public. Nonetheless, he asked that residents keep their guard up.

"It's a good reminder to keep lights on at your door, keep your doors locked and have a peephole so if someone knocks on your door you can identify them and if you don't know them, call 911," Fujii said. "We live in the safest big city in the United States, but you still have to be careful and protect yourself."

Fujii also asked for the public's help. "Call 911 or Crimestoppers if you know anything about either of these cases," he said.