After running more than 26 miles, the Boston Marathon finish line was just ahead for Minnesota marathoner Pat Sauter. Then a “huge boom” shook the earth and brought him and a stream of other runners to a standstill.

Seconds later, a second explosion about 50 yards in front of him shook him out of a state of confusion. “Everyone went into a panic.”

People were screaming. Children were crying. Bloodied, injured spectators lay on the ground. “One person was missing a limb,” Sauter said.

Cops and race security officials screamed directions. A rescue worker carried a small boy who was bleeding from the head.

“A guy came toward me, his clothes burned or torn off,” Sauter said. “He had soot all over. It was just chaotic.”

The blasts, which erupted about 100 yards apart in the streets near the finish line, killed three people and injured more than 140 others during what is the Holy Grail of marathons and an attraction that draws about 500,000 spectators. About 500 Minnesotans lined up at the marathon’s start along with 23,000 other runners.

“I don’t know what a bomb sounds like,” said Sauter, a 63-year-old Minneapolis attorney who has run more 60 marathons and was just about to finish his third in Boston. When the first explosion shook the street, Sauter figured organizers had set off a boom “to make the finish” special. Or, maybe it was a construction mishap, he thought.

“A guy in front of me hit the ground,” Sauter said. “I wasn’t smart enough to do that. I wasn’t thinking very well.” But within seconds, the second explosion and the plume of smoke rising from two areas along the side of the runners’ finishing chute made it clear that something was very wrong.

“I knew [then] it was a bomb,” Sauter said. “The embarrassing thing is that I didn’t know what to do when it happened. Do you charge toward the bomb to help the victims, or do you flee? You’re just stunned and don’t know what to do.”

Runners began to break through the sideline barriers to get inside nearby buildings, Sauter said. But police and security officials yelled for everyone to get out of the buildings.

So he followed the directions of the police as chaos erupted around him. “It was just a madhouse. ”

Lakeville runner Paul Stein was in the finisher’s chute getting his medal for his eighth Boston run when he heard the blasts. Runners scattered, some sprinting out of the chute, others trying to make their way to relatives and friends who might be waiting nearby. “No one had a clue what was going on.”

Kevin Schooler, 42, of Plymouth, was about two blocks away.

“Everybody stops in their tracks and sees a big puff of white smoke,” said Schooler, a major in the Army National Guard who has done two tours of Iraq and just barely completed his second Boston Marathon.

“No one sees the blast itself, and then as we’re looking, a second explosion goes off,” Schooler said. “That was the first thing that told me that it was.”

Schooler said that runners and others around him “were starting to get nervous realizing this isn’t just a manhole cover or a transformer explosion. . . . It seems like people were ready to panic and run.”

He said his time in Iraq gave him his “share of explosions. I said to everybody to stay calm, and then the police took over."

Schooler said he was expecting to see his wife, Ann, near the finish line, but he couldn’t find her. His concerns for his own safety quickly shifted to Ann.

He called her cell phone. Nothing. Texted. Nothing again. He tried relatives back in the Twin Cities. Maybe she checked in there. Again, nothing.

“After a while, I couldn’t get a cell,” he said. “Normally, she is in that area near the finish line.”

Turns out, she bumped into another Minnesota runner’s wife, and the two were on a train to the 25-mile mark when the explosions went off.

They finally met up at the spot where runners pick up the warmup garb that they shed at the start of the race.

Reunited and a bit shaken, Kevin and Ann Schooler were back in their room at the Four Seasons, less than four blocks from the finish line and under a mandatory lockdown.

Catching his breath and with time to think about his fate, Schooler said he picked a bad time “to run my slowest marathon . . . I didn’t realize I was that close.”

Tim Wright of Sauk Rapids, after finishing his fourth Boston Marathon, was changing into dry clothes when a “humongous” blast erupted and smoke rose into the air. Within minutes, runners in tears streamed by him. “We all knew something very bad was happening.”

Eventually runners and spectators made their way through the chaos to the safety of hotels and other lodging. But back home in Minnesota, family and friends waited anxiously, watching news reports and frantically trying to reach runners with little luck because cellphone services were being overtaxed.

“I tried to stay positive,” said Kathy Sauter, who had followed her husband’s progress via texts until they suddenly stopped. She waited 2½ hours before she got the text from her husband that he was OK.

“I must have sent the same text to her half dozen times but it wouldn’t go through,” said Pat Sauter.

Staff writer Abby Simons and the Associated Press contributed to this report. pwalsh@startribune.com • 612-673-4482