VIDEO: What Is Believed to Be Pipe Bomb Detonated by Bomb Squad

(NECN: Boston, Mass.) - Police conducted a controlled detonation in the area of Commonwealth Avenue and Charlesgate on Friday morning.

A police source tells NECN that police believe it was a pipe bomb.

NECN photographer Sean Colahan captured it on camera.

Residents of Watertown, Waltham, Newton, Belmont, Cambridge and Allston/Brighton reminded to stay indoors.

Authorities say two suspects in the Boston Marathon bombing have killed an MIT police officer, injured a transit officer in a gunfight and threw explosive devices at police during their getaway attempt.

One is dead and the other is still at large.

The Boston bombing suspects have been identified to The Associated Press as coming from the Russian region near Chechnya.

A law enforcement intelligence bulletin obtained by the AP identified the surviving bomb suspect as 19-year-old Dzhokhar Tsarnaev.

Officials tell AP both men lived legally in the U.S. for at least a year.