The first clue to Alicia Harrison that something was wrong came when the runners in front of her reached a halt and formed a wall of confused people in the middle of the road.

“They just abruptly stopped the race,” said Harrison, an Austin resident who had gone to watch and run a portion of the Boston Marathon Monday. “It was just chaos. Nobody knew why.”

About half a mile away and out of earshot of Harrison, two bombs had exploded in the packed streets near the finish line. The blast killed at least three people and injured more than 130 in a terrifying scene of shattered glass, billowing smoke, bloodstained pavement and severed limbs, raising alarms that terrorists might have struck again in the U.S., authorities said.

Though Harrison hadn’t qualified for the marathon, she had been running the second half of it for her own enjoyment. She typically goes on runs of 10 to 13 miles, and hoped to make it into the 26.2-mile race next year. When runners ahead of her came to a stop, Harrison said, she didn’t feel like she was in danger, but she knew the cause must have been serious.

“Police weren’t taking time to really speak to people,” she said, adding that the streets were packed with emergency vehicles and personnel “as far as you could see.”

“I just thought I needed to get out of the way,” she said.

She didn’t see any of the injured, and would later find out about the bombs from a TV report. In the meantime, however, she and many others were trying to figure out where to go. The cell phone grid had been shut down to prevent people from detonating explosives using their phones, but it also meant confused runners and spectators had no way of finding their friends and families. The marathon’s alphabetized meeting place had been closed off because of its proximity to the finish line. It took Harrison’s phone an hour and a half to regain its signal.

“The most concerning thing was that people weren’t able to find anyone,” Harrison said, adding that when she finally did contact friends and family they were extremely relieved. She was fine, but she hoped not too much trauma had come from the incident.

No one from Austin or Albert Lea registered for the race, although a friend and colleague of Albert Lean Amy Wasson finished in 3 hours and 44 minutes — just 25 minutes before two bombs exploded 4 hours and 9 minutes into the race.

Wasson said the friend was fine, but she was stuck downtown in the chaos while her boyfriend was at a hotel.

Wasson and her husband, Jeff Miller, are runners, and Miller has qualified for the 2014 Boston Marathon. He plans to run, despite the tragedy.

“There are too many people, too many opportunities to be afraid of this stuff,” he said.

Wasson said they have two other friends who ran the Boston Marathon, and they are also fine.

“Thank God for Facebook,” she said. “That’s how I found out about my friends.”

She said they know a man from Mankato who crossed the finish before the blast and they knew another man whose wife was spectating. All were safe and back at their hotel watching the TV news.

Albert Lea woman Lori Alexander said her niece, Tori Cowles, ran the marathon, too. She finished at 3 hours and 15 minutes and texted her aunt that she was unhurt.

“She said the city is just pure chaos,” Alexander said.

— The Associated Press contributed to this report.