By Phil Gast, Eric Levenson and Jessica Suerth, CNN
(CNN) -- A natural gas explosion at Minnehaha Academy in Minneapolis on Wednesday collapsed part of the building, killing two people and hospitalizing nine others, officials said. The explosion was caused by contractors doing work on the building, Minneapolis Assistant Fire Chief Bryan Tyner said.
The fire department had been searching Wednesday night for an individual who had been reported missing when they found the second body, Minneapolis Fire Chief John Fruetel told reporters.
Authorities had not identified the victims as of Wednesday night, but said those killed were both staff members from Minnehaha Academy.
In separate statements, Minnehaha Academy identified the victims who were killed in the gas explosion as receptionist Ruth Berg and staff member John Carlson.
Berg worked for the school for 17 years, the school said in a statement. "As our receptionist, she welcomed everyone with a smile and was always willing to go the extra mile to help our students, families, and staff," the statement read. "She will be greatly missed. Please keep Ruth's family, and our school community, in your prayers."
Carlson was an alumnus and staff member, the school said, who was "Minnehaha's biggest cheerleader and a long-time presence in the school."
"He graduated from Minnehaha in 1953, sent his children here, and after retiring from his first career he came back to work at the school. John will be deeply missed," the statementread.
Fruetel said all construction workers who had been renovating the building were accounted for, and Minnehaha Academy said all its summer program students and staff were also accounted for.
The nine people who were injured were taken to the Hennepin County Medical Center, but five have since been discharged. All are adults. One of the victims remains in critical condition, while the other three are satisfactory.
Dr. James Miner of Hennepin County Medical Center told reporters the patients had fractures and head injuries, but no burns.
Explosion caused by contractor work
Two floors in the center section of the building collapsed over a sub-basement, Fruetel said, and there was heavy damage all through the school. The structural integrity of the building is still in question.
Becca Virden, a spokeswoman for CenterPoint Energy, said crews were called to the area of a school boiler room to assist first responders and make the area safe.
The Christian school said there was a gas leak and explosion at its multistory Upper School, which houses grades 9-12. The academy has about 825 students in grades pre-K through 12, housed on two campuses. The 2017-18 school year is set to begin August 23.
"I would imagine it would have been a lot more significant if it was (during) school time," Tyner said. "It is a good thing that it's the summertime and probably limited the amount of people that were in the building."
Witnesses detail harrowing scene
First responders said it looked like a "great big hole" in the building where the collapse occurred, with flames shooting from one side of the building. Officer Dean Milner said two civilians on scene helped rescue one man who was buried beneath the rubble.
Milner said officers were battling through thick flames and the smell of gasoline to rescue the unidentified adult male. Officers also warned people nearby to get away in case of a second explosion.
Officer Vicki Karnik, one of the first responding officers on the scene, said the explosion reminded her of the 2007 Minneapolis bridge collapse that killed 13 people and injured 145.
"I was kind of having a flashback, especially with it being 10 years ago [yesterday]," she said.
Video broadcast by WCCO showed smoke and flames rising from the debris.
Jack Mahler was warming up for a soccer practice nearby when he heard two sprinting men yelling "Gas!" and "Get out!" Shortly after, there was a huge explosion that knocked him off his feet, he told WCCO, "and then it was just kinda chaos from there."
Three people on the roof of the school needed assistance getting down, officials said.
John Barron, who lives across the street from the academy, told the station the blast shook his windows and startled his dogs.
"I saw that where the building used to be one continuous building, (it) now had a gap," he said. "I could see sunlight all the way through to the other side."
Gov. Mark Dayton pledged resources for first responders. "I thank the many firefighters, paramedics, and law enforcement officers who rushed to the scene this morning, and who are working still to ensure the safety of our children, adults, friends, and neighbors," he said in a statement.
Friends, loved ones mourn victims in vigil
Hundreds of friends, neighbors, co-workers and community members gathered for a vigil Wednesday night for the victims of the explosion. The vigil was held at the Minnehaha Academy Lower & Middle School, which quickly filled.
Jeff Wagner, a WCCO reporter, tweeted that many of the mourners donned Minnehaha Academy clothes and colors as they bowed their heads in prayer and joined hands in song.
The vigil lasted more than an hour and included speakers who emphasized the importance of retaining a religious faith in times of tragedy and praying for those who have been affected by the incident.
"Let this be a reminder to each and every one of us, no one got up this morning thinking that this was going to happen," one of the speakers at the vigil said. "People were just going to work, people were just serving in their position."
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