As the sun rose on Boston Tuesday, its Back Bay area had become a virtual police state.
Officers and the National Guard were everywhere. It was obvious the law enforcement meant business. It was so different from the way Monday began.
D.C. resident Rachel Ackerman is a rabbi in Chevy Chase who was thrilled to be running the marathon for the second time.
"It's a great energy, great marathon, wonderful spectators," she says.
She finished and wanted to go back to see others finish. Then everything changed. She hadn't made it very far past the finish line when she heard the first boom.
D.C. resident Colleen Nelson was in a crowd of runners who'd finished.
"I could hear screams in the distance, and a few seconds later there was a second boom," she says.
Colleen's husband Eric was waiting not far away, growing increasingly worried. Finally, he saw her.
"I went up to her immediately, I gave her a hug, and I told her, I said, 'Babe, I think something really bad just happened,'" he says.