MINNEAPOLIS (WCCO) – Jack Mahler was warming for soccer practice Wednesday morning outside Minnehaha Academy’s Upper School when two men rushed out of the building yelling, “Gas!”, “Get out!”

One of the men ran along the side of the century-old south Minneapolis school, telling people to immediately leave the building. The other man rushed down the street. When he got to the end, an explosion split the building in two.

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“Huge explosion,” Mahler said. “Knocked me off my feet…and it was just chaos from there.”

In the school gymnasium, Tramon Vanleer, the assistant basketball coach, was working with student athletes when the blast rocked the school.

“It sounded like a large door slamming,” he said. “At the same time, the lights went out and debris started falling from the ceiling.”

Vanleer says he and the students ran out of the gym “as fast as possible.”

Outside, students and neighbors checked to see if anyone was hurt and called police. Emergency crews were on the scene in minutes.

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The explosion, which occurred around 10:30 a.m., gutted the central part of the Upper School. Initial helicopter footage showed the resulting fire, which burned for more than an hour after.

Minneapolis police say contractors working on the building ruptured a gas line, causing the explosion.

School officials say longtime receptionist Ruth Berg died in the blast. The body of another staffer, 81-year-old custodian John Carlson, was discovered late Wednesday evening.

The explosion sent nine people to the hospital, and one person remains in critical condition. He was identified as the school’s assistant soccer coach, Bryan Duffey.

So far, five people have been released from the hospital.

Minnehaha Academy says none of its summer program students were hurt.

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Hundreds attended a vigil for the victims Wednesday night at Minnehaha Academy’s Lower and Middle School.