(CNN) -- Denver police opened a homicide case Wednesday after firefighters found five people dead inside a bar that was set ablaze.
Police said they believe the bar was set on fire to mask the homicides inside.
"We'd like to say this was an isolated incident, but I can't say that with any certainty," Denver Police Chief Robert White said Wednesday afternoon as he asked members of the public to help investigators.
Police said they had received tips, but had no suspects yet.
"We're asking if anyone has any information, no matter how trivial they think it is, please contact us," White told reporters.
Reports of a fire at Fero's Bar and Grill came in around 1:50 a.m. Wednesday. Firefighters working to put out the blaze found four women and one man dead, police said.
"Each victim's body showed obvious signs of trauma indicating that a homicide investigation is warranted," police said in a written statement.
Authorities did not identify the victims or release further details about their cause of death.
Arson investigators were also looking into what caused the fire, police said.
CNN's AnneClaire Stapleton and Shawn Nottingham contributed to this report.