The app indicated that Maggie was still moving, a relief for her parents. Mary Beth Aasen tried in vain to call her daughter for about 30 minutes before Maggie called her.
"When I talked to her she was pretty upset," Aasen said.
Kim Hauser, a substitute teacher in the Chicago area, did not know about the explosions until her students went home and she got a chance to look at her phone. There were messages from acquaintances asking, "'Is your brother OK?" She searched the news and it dawned on her why they were asking.
"I tried to call him immediately, but there was no cell service," the Frankfort, Ill., woman said. "I waited anxiously by the phone. I just felt horrible. I had a hard time holding myself together."
Five minutes became 10, then 20 — finally, 45 minutes later she looked down to see a text from her brother, Thomas Wiora. He had crossed the finish line shortly before the explosion and was 120 yards away when it went off. But he was fine.
"I was relieved," she said. "But the whole thing was so heartbreaking."
Mary Butler, of Oklahoma City, hadn't been able to reach her husband, Jason, who was running with his son, brother and other family members. But she said he'd posted on Facebook that he and the others were OK.
"That's all I know about it," Mary Butler said, adding she'd been trying to call since she'd first heard of the explosions. "I'm just waiting — keep trying to call."
She declined to talk further so that she could keep her phone line open.
Associated Press writers Scott Bauer in Madison, Wis.; Kevin Begos in Pittsburgh; Kristi Eaton in Sioux Falls, S.D.; Dan Holtmeyer in Oklahoma City; David Mercer in Champaign, Ill.; Dinesh Ramde in Milwaukee; Dan Sewell in Cincinnati, Michael Tarm in Chicago and Allen Breed in Raleigh, N.C., contributed to this report.