The U.S. Justice Department said Thursday it will open a wide-ranging civil rights investigation into the use of force by Cleveland's police department, whose officers fired 137 shots at the end of a massive police chase last fall, killing two likely unarmed people.

Assistant Attorney General Thomas Perez said the investigation will look beyond the November car chase that involved more than 60 patrol cars and ended in the shootings of Timothy Russell, 43, and his 30-year-old passenger, Malissa Williams.

Perez said the probe will not be a criminal investigation; its focus is the entire department, not individual officers. It will analyze several years of excessive force claims as well as police policies, training and procedures, he said.

"We go into this with no preconceived notions," Perez said at a news conference in Cleveland.

City leaders had asked the federal government to review Cleveland police division policies after that chase, which raised questions about the conduct of officers. But Perez said there was not one tipping point that led to the wider investigation.

Cleveland Mayor Frank Jackson said he welcomed the expanded investigation. "It is vital that there is a level of trust between police and the community," he said.