These reports don't add up:
CNN here, where the video doesn't show the boat covered in a blue tarp but white, casting doubt on the credibility of what the stepson says but CNN seems to accept as fact anyway:
Henneberry [the homeowner] climbed a stepladder to look inside. "He basically stuck his head under the tarp (and) noticed a pool of blood," Duffy said. It was dark under the tarpaulin, so the boat owner could only make out vague contours, "but he definitely noticed there was something crumpled up in a ball," the stepson said. A pool of blood; a manhunt in Watertown; time to call 911. Squad cars with lights flashing raced in and lined the streets. Officers fanned out around the house. ... Duffy said he tried frantically to call his mother and stepfather as he watched on TV while law officers unleashed a hailstorm of gunfire into the backyard.
UK Daily Mail here, whose photos clearly show not a blue tarp but white, quotes the police spokesman unaccountably ringing the same bell that Tsarnaev was too out of it to resist:
'He had lost a lot of blood. He was so weak that we were able to just go in and scoop him up,' state police spokesman David Procopio told the Boston Herald adding that the suspect was in 'serious if not critical condition'.
Another video of gunfire, here, which is mostly noteworthy for what you hear, not what you see:
