Police say they have video that shows a man who was under surveillance by terrorism investigators lunged with a knife at a police officer and an FBI agent before he was fatally shot.

Police Commissioner William Evans says members of the Joint Terrorism Task Force approached Usaama Rahim outside a pharmacy Tuesday morning to question him. Evans says Rahim went at the officers with a large military-style knife.

A law enforcement official with knowledge of the investigation said Rahim had been making threats against law enforcement. The official was not authorized to release details and spoke on the condition of anonymity.

Rahim's brother says in a Facebook posting his brother was confronted by three officers while waiting at a bus stop to go to work. He says his brother was shot in the back three times.