Boston Police Commissioner Ed Davis, at podium, speaks while accompanied by State Police Col. Timothy Alben, second from right, and Massachusetts Governor Deval Patrick, right, during a news conference, after the arrest of a suspect of the Boston Marathon bombings in Watertown, Mass., Friday, April 19, 2013. WASHINGTON (AP) - Boston's police commissioner says the lone surviving suspect in the Boston Marathon bombing is in serious condition and authorities have not been able to try to interrogate him. Commissioner Edward Davis also tells CBS' "Face the Nation" that the crime scene from the early Friday firefight in Watertown, Mass., was "littered" with unexploded improvised explosive devices. Davis says it's his belief that 19-year-old Dzhokhar Tsarnaev and his 26-year-old brother Tamerlan "were going to attack other individuals" - and Davis says that's based on the evidence at the scene and the firepower that the brothers had. Tamerlan died in the gunbattle with police in Watertown. Davis says "this was as dangerous as it gets in urban policing."