After running 26.2 miles in four hours on little food and water, University of Minnesota alumna Brittany Pentek needed Gatorade and a change of clothes.

Jennifer Bhalla, a lecturer in the University’s School of Kinesiology, had just returned to her hotel room after finishing her second Boston Marathon.

Then the bombs went off.

The women were blocks from where two bombs exploded Monday at the finish line of the Boston Marathon — an attack that killed three people and wounded more than 170.

“I just said ‘What was that?’ That was not a normal noise for a marathon finish,” Pentek said.

FBI investigators found the bombs consisted of explosives placed in 1.6 gallon household pressure cookers inside black duffel bags. One bomb was packed with nails and the other contained shards of metal and ball bearings.

President Barack Obama deemed the attack an act of terrorism Tuesday.

He said in a statement that “America is strong and resilient … and won’t let cowardly acts get in the way of our lives.” He also promised the full force of the law in trying to “uncover whoever was responsible.”

It’s not known if the bombing was the work of a single person or a group.

Sen. Scott Dibble, DFL-Minneapolis, also competed in the marathon and finished before the explosion but didn’t see or hear anything, Minnesota Public Radio reported.

‘Anxiousness in the air’

Pentek boarded a bus at 4 a.m. on Monday to take her to the site where she’d begin the Boston Marathon seven hours later.

Pentek qualified to compete in Boston last year at the Eau Claire Marathon after taking the University’s marathon training class.

While on the bus, Pentek was struck by the wide variety of people the marathon attracted.

About 23,300 people competed in the Boston Marathon this year — 452 from Minnesota, according to the Boston Athletic Association.

“You feel like you’re in a different world at that point, like you’re in a global community,” Pentek said.

She started the race feeling good but said the last stretch was tough. She decided to stop at a medical tent in order to subdue the cramping in her legs before finishing the marathon.

After completing the race fueled by crowd support and a handful of jellybeans, Pentek said all she wanted to do was find food, water and warm clothes, but she felt she had conquered something.

Pentek was changing clothes in a tent about four blocks from the finish line, she said, when she heard a muffled boom. As she walked toward the site of the explosion, she felt “anxiousness in the air.”

“People were embracing,” she said. “But not embracing because ‘Hey, you finished the race!’ they were embracing because, ‘Hey, you’re alive.’”

A good start

Bhalla, who’s been running marathons for nearly 15 years, said the Boston Marathon is one that most runners strive to compete in and that this year’s was off to a good start.

“It was an awesome day,” Bhalla said. “It was beautiful weather and everything was perfect.”

She said she finished the race satisfied with her time and then walked to her hotel near the finish line.

Soon after, she said a friend told her a bomb had gone off near the finish line.

Bhalla figured she missed the explosion by about 20 minutes.

“At first I was in disbelief, and then I just felt a deep sadness,” she said.

Cellphone service at the time was disconnected, so Bhalla updated her Facebook status to let her friends and family know she was OK.

“I don’t have any idea why someone would do something like this,” she said, “but I don’t think it will stop me from running again in Boston.”

—The Associated Press contributed to this report.