Federal investigators said a Milwaukee man was stockpiling explosives in Germantown, and when they closed in, he killed himself. But his family doesn't buy it and is conducting its own investigation. The incident started at a Germantown storage facility. A Bureau of Alcohol, Tobacco, Firearms and Explosives task force showed up with a search warrant in search of explosives they believed a man was stockpiling in his locker. The warrant said investigators removed three pages of evidence from the locker, including empty grenades and ammonium nitrate -- the fertilizer used to bomb the federal building in Oklahoma City. A tipster told them 40-year-old Bruce Young wanted to kill people who'd wronged him. What happened next has gone viral on Facebook. Video shows the agents and Young as he ran away from them near 34th Street and Greenfield Avenue in Milwaukee last week. The camera captured a police vehicle, which the ATF confirmed was operated by one of its agents, as it knocked Young to the street. "This was a completely avoidable death," attorney John Birdsall said. Birdsall represents Young's family. Wisconsin's Department of Justice is investigating the incident and told WISN 12 News, "The cause of death was a self-inflicted gunshot wound and not being struck by the vehicle." "The family does not believe that, and I have great reservations about that conclusion," Birdsall said. The warrant said Young used drugs to deal with stomach cancer and his fiancee's recent suicide. His family said it wants someone held accountable. The family's first step in its investigation will be an independent autopsy on Thursday.

Federal investigators said a Milwaukee man was stockpiling explosives in Germantown, and when they closed in, he killed himself. But his family doesn't buy it and is conducting its own investigation.

The incident started at a Germantown storage facility. A Bureau of Alcohol, Tobacco, Firearms and Explosives task force showed up with a search warrant in search of explosives they believed a man was stockpiling in his locker.

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The warrant said investigators removed three pages of evidence from the locker, including empty grenades and ammonium nitrate -- the fertilizer used to bomb the federal building in Oklahoma City. A tipster told them 40-year-old Bruce Young wanted to kill people who'd wronged him.

What happened next has gone viral on Facebook. Video shows the agents and Young as he ran away from them near 34th Street and Greenfield Avenue in Milwaukee last week.

The camera captured a police vehicle, which the ATF confirmed was operated by one of its agents, as it knocked Young to the street.

"This was a completely avoidable death," attorney John Birdsall said.

Birdsall represents Young's family. Wisconsin's Department of Justice is investigating the incident and told WISN 12 News, "The cause of death was a self-inflicted gunshot wound and not being struck by the vehicle."

"The family does not believe that, and I have great reservations about that conclusion," Birdsall said.

The warrant said Young used drugs to deal with stomach cancer and his fiancee's recent suicide. His family said it wants someone held accountable.

The family's first step in its investigation will be an independent autopsy on Thursday.