By Alex Dobuzinskis

LOS ANGELES (Reuters) - Four homeless people were found dead on Tuesday inside a burned-out office building near downtown Los Angeles, bringing to five the death toll from a fire a day earlier that led to the arrest of a man suspected of igniting the flames, officials said.

Johnny Sanchez, 21, who was himself believed to have been homeless, was arrested on suspicion of murder, Los Angeles police spokesman Mike Lopez said in a phone interview.

Los Angeles police Captain William Hayes told reporters on Tuesday that Sanchez's intent in lighting the fire was to kill at least one other person living in the vacant two-story office building.

It took more than two hours for firefighters to put out the massive blaze on Monday night, fire officials said in a statement.

As they were extinguishing the flames, firefighters found the body of one person who they believed to be homeless, and another injured victim who was rushed to a hospital, the statement said.

On Tuesday, a team with search dogs combed through the charred ruins of the structure and discovered the bodies of four more apparently homeless people, raising the death toll to five, the statement said.

Helicopter news footage of the fire's aftermath from an NBC affiliate television station showed most of the building's roof caved in, with blackened debris spread out all along the second floor.

Firefighters have not released the names of the victims.

It was not immediately clear if Sanchez had obtained an attorney.

(This story corrects paragraph 3 to show Captain William Hayes is with Los Angeles police, not the fire department)

(Reporting by Alex Dobuzinskis; Editing by Steve Gorman and Sandra Maler)