"We had no idea what was going on and then we heard the second blast."
Runner's World magazine, based in Emmaus, had several staffers in Boston today for the marathon.
Magazine officials say all their staffers are safe and shared updates on its website.
"The blasts went off very close to each other. It shook the floor," Brand Editor Warren Greene said, according to the site.
Runners nearing the finish line after the blasts became congested, according to the report from Editor-at-large Amby Burfoot.
Burfoot was about three-quarters of a mile from the finish when he hit the wall of runners. "Everyone's cell phones starting going off. I got a call from (my wife) Cristina that the finish line was cleared and the race was over," he reported on the magazine's site.
"All the spectators and people on the course turned and ran the opposite direction. I didn’t finish – I went straight into the mall," Hamilton reported on the Runner's World site.
Runner's World spokesman David Tratner said a large part of the staff was in the city this week and they've all been account for.
Bart Yasso, a Runner's World executive, posted on Facebook that he was in the food court when he heard the two explosions.
"When I walked outside I could see smoke from the second blast," he wrote. "I witnessed first responders running to the danger zone, putting our safety first without regard for their own safety. The medical tent at the marathon line finish line treated lots of the injured.
"I spoke to lots of dazed runners that just didn’t understand the extent of the situation because they were still on the course hoping to finish the marathon. Please say a prayer for the victims and their families."
Runner's World Editor David Wiley was tweeting shortly after the explosion saying that the media center was locked down.
Greene, who was at an industry event at the finish, described confusion and a hectic scene for the magazine.
"The barricades fell away and folks started running every which way. The cops came in and shut the finish area down. The race stopped. Runners just stopped running and looked at the finish."
Reporter Sara K. Satullo contributed to this report.