Brigham and Women's nurses witnessed bombings

It's not something you see every day. Police officers standing guard -- automatic weapons in hand -- at the entrance to Brigham and Women's Hospital on Tuesday.

"It's actually kind of shocking. It kind of reminds me, I wasn't there, but it reminds me of 9/11," said Chris Reardon.

"It's a little unnerving, but I feel safe in the building, that they're here and I'm proud to be an American," said Jennifer Barry.

Barry and Kathy McPherson are registered nurses. On Monday, they were in the thick of the chaos on Boylston Street as they were cheering on a group of nurses running in the marathon.

"The bombs went off on either sides of us. Fortunately, we were in the middle of both of them and weren't hurt, but we saw plenty of people that were," McPherson said.

About 31 patients were rushed to Brigham and Women's, including Newport resident Heather Abbott. Doctors said they removed objects from at least three patients that they say were built into the explosives.

"These objects are ball bearing-type or small shot-type, just a little larger than BB, round metallic beads," said Dr. Ron Walls.

Walls said doctors also removed over a dozen small carpenter-type nails.