May 1 (UPI) -- A large fire in Sao Paulo, Brazil, killed at least one person Tuesday after flames engulfed two high-rise buildings -- causing one to collapse.
The 20-story building crumbled as flames shot toward the top floor.
About half of the floors in the second building were also engulfed.
Three people were reported missing.
More than 150 firefighters battled the blaze, which authorities believe was caused by a gas explosion.
Authorities said the toll could rise as more people could've been trapped inside. Witnesses said they saw several people stranded, hollering for help on the buildings' roofs.
The building that collapsed, once a federal police headquarters, had been occupied by squatters.
Sao Paulo Fire Department officials said as many as 50 families could have been living there.