Police Audio From Watertown Shootout Released

WATERTOWN (CBS) - CBS News has obtained the audio from the shootout between police and the Boston Marathon bombing suspects that took place in Watertown early Friday morning.

The gunfight followed a chaotic chase through Cambridge that began with the fatal shooting of an MIT police officer at about 10:30 p.m. Thursday.

"They have explosives, some type of grenades," an officer says on the radio. Then he reported, "Loud explosions, loud explosions, loud explosions."

State Police say numerous pieces of evidence was recovered from the scene including evidence of homemade explosives, including pipe bombs and the pressure cooker, as well as more than 200 spent rounds.

An MBTA transit police officer was injured in the firefight.