SÃO PAULO, Brazil — A high-rise tower in São Paulo, Brazil, collapsed early Tuesday after a fire raged through the building and spread to two other structures nearby. At least one person was believed to have died.

The collapsed building, which reached more than 20 stories high, was a former federal police facility that was inhabited by about 150 squatters, city officials said, but it appeared that the vast majority of them escaped the blaze.

The blaze highlighted the shortage of affordable housing in the city. Márcio França, governor of São Paulo state, estimated that 150 downtown buildings in the city are illegally occupied by squatters, living in substandard conditions.

A person was trapped on an upper floor and was calling for help when the building collapsed, and it is very likely that the person was killed, a spokesman for the São Paulo Fire Department said. He said firefighters had conducted interviews with many people who had lived in the building intermittently, trying to determine whether anyone else might have been inside when it collapsed.