• A pressure-cooker bomb is believed to have been used at one or both of the explosion sites. The FBI announced Tuesday afternoon that investigators have recovered crime scene evidence including "pieces of black nylon, which could be from a backpack, and fragments of BBs and nails possibly contained in a pressure cooker device." The evidence is being shipped to an FBI lab in Quantico for analysis.
• Authorities called for tips from anyone who witnessed a person carrying a dark, unusually heavy bag in the vicinity of the bombing. In addition they asked the public to report anyone who had been talking about a pressure-cooker bomb or "the marathon, or about the date of April 15 in any way." "Someone knows who did this," FBI agent Rick DesLauriers said.
• President Obama will attend an interfaith prayer service in Boston Thursday morning, the Massachusetts governor announced. The president has canceled a trip he was to take to Kansas on Friday. More than a dozen vigils were planned in Boston for Tuesday and Wednesday.
• Three people were killed in the attack, including Krystle Campbell, 29, and Martin Richard, 8. The third fatality is believed to have been a graduate student at Boston University. The school confirmed the death but did not name the victim "pending permission to do so from the family." At least 176 people were wounded in the attack. An unknown number remain in critical condition. Other patients showed improvement.
• No suspects have been identified and no motive has been determined in the marathon bombing, authorities said.
• The city of Boston has established a fund, called One Boston, to provide for victims of the attack and their families.
