New Delhi, March 21 -- Four Brazilian police officers have been removed from street duty in an investigation into their involvement in a deadly raid in a low-income part of Rio de Janeiro that killed seven suspected drug traffickers and also left one resident dead, authorities said Friday.

The decision follows preliminary analysis of Wednesday's operation in the Prazeres favela, in central Rio near the bohemian neighborhood of Santa Teresa, which found the "improper use" of body cameras, Rio state's military police said in an email to The Associated Press. They did not elaborate on what was meant by improper use, or whether they may have been switched off during the raid.

The officers involved were transferred from operational duty to a...