Police still investigated the cause of the fire which occurred on Sunday at around 8 a.m. local time, Inspector Satu Ristitanto, Head of the Sawahan Police Sector's Criminal Investigation Unit, said here on Sunday.
"We are still trying to identify the victims," he said.
A total of 22 fire trucks from the Surabaya City Government Fire Service were deployed to extinguish the fire.
Head of the Criminal Investigation Unit of the Surabaya Police, Adjunct Senior Commissioner Sudamiran, said the fire was successfully extinguished at around 10:30 a.m. local time.
One of the five victims was a woman aged around 60 years old.
The other three victims were believed to be her children and grandson.
"The youngest victim aged 15 years is the grandson of this woman," he said.