Authorities determined early on that it was intentionally set and started a homicide investigation, said Joe Montoya, division chief investigations at the Denver Police Department.
Djibril Diol was an engineer and the brother of Hassan Diol.
All five were in the lower part of the home while three people on the second story jumped to safety, CNN affiliate KMGH reported.
Greg Pixely with the Denver Fire Department said a police officer attempted to rescue people from the home but was pushed back due to the heat from the fire, KMGH reported.
Denver Mayor Michael Hancock expressed his condolences to the victims' families as did Macky Sall, the president of the West African nation of Senegal, who said he's closely following the investigation.
Hancock urged people to donate to the family's GoFundMe account to help send their remains to Senegal.
The venerable actor underwent a tracheotomy which has completely altered his voice and can sometimes make communicating difficult.
But Kilmer's not letting it stop him.
Kilmer not only has a role in the recently delayed "Top Gun" sequel, but he also has another forthcoming film.
"Paydirt" finds Kilmer co-starring with his 28-year-old daughter, Mercedes, who plays his daughter in the movie.
Val Kilmer went public with his cancer diagnosis in 2017 after initially denying reports he was ill.
In April he released a memoir, titled "I'm Your Huckleberry" -- a famous line of his from the 1993 film "Tombstone" -- which traces his career, including memorable roles playing legendary singer Jim Morrison in the big screen biopic about The Doors frontman.