The FBI says a man being questioned by authorities in the Boston Marathon bombing probe was fatally shot when he initiated a violent confrontation.

Tamerlan Tsarnaev waits for a decision in the 201-pound division boxing match during the 2009 Golden Gloves National Tournament of Champions (Glenn DePriest/Getty Images)

The shooting incident early Wednesday took place in Orlando, Fla., where an FBI agent along with other law enforcement personnel were interviewing Ibragim Todashev, 27, who was not a suspect in the case according to NBC News.  He was being questioned as part of an effort to speak with anyone who had contact with Tamerlan Tsarnaev, the older brother in the bombing investigation.

Todashev knew Tamerlan when they were fighters. Todahev was being questioned about his connection to an  unsovled triple murder in Waltham, Massachusetts in which all three victims' throats were slit and their bodies covered with marjiuana.

Todashev, who had been co-operative in previous interviews, attacked an agent. In a  statement, FBI spokesman Paul Bresson said the FBI agent acted on an imminent threat and shot & killed Todashev.

The FBI agent was transported to a hospital with non-life threatening injuries.

Todashev had some connection to radical Chechen rebels but it's not known his possible role radicalizing Tamerlan.