Flashbang grenades, which have become a common tool in police raids, are intended to disorient criminal suspects, not kill or seriously wound them. But that’s precisely what has happened to some victims of the devices developed by the U.S. military.

An investigation by ProPublica found evidence of at least 50 Americans, including police officers, have been seriously injured, maimed or killed by flashbangs since 2000. The investigative news website said the total is probably far higher because few records are kept on deployment of flashbangs.

Although flashbangs don’t release shrapnel during their explosions like conventional grenades, they still can inflict serious wounds if they explode next to a human body.

Their flash powder is hot enough to cause second-degree burns on flesh, and the concussion from their blast has been shown to sever hands and fingers, cause heart attacks, burn down homes and kill pets, according to ProPublica.

Some police forces report using flashbangs up to 80% of the time during their raids on buildings. Those subject to the police raids are often found to be innocent or guilty of only minor offenses.

An investigation by the American Civil Liberties Union (ACLU) found that the city of Little Rock, Ark., used flashbangs on about 84% of its raids, nearly all of them in homes in predominantly black neighborhoods. The Little Rock police department issued a statement defending the practice, but the ACLU found that three-quarters of the raids netted no weapons and often only small amounts of marijuana.

-Noel Brinkerhoff, Steve Straehley

To Learn More:

Hotter Than Lava (by Julia Angwin and Abbie Nehring, ProPublica)

What Killed Aiyana Stanley-Jones? (by Charlie LeDuff, Mother Jones)