MINNEAPOLIS - One person is dead and another is still missing after a building exploded and collapsed at Minnehaha Academy, according to the Minneapolis Fire Department.

Minneapolis Fire Chief John Fruetel said Wednesday afternoon that one victim, who was previously reported as missing, was found dead in the rubble.

Minnehaha Academy confirmed just before 5 p.m. that the victim is Ruth Berg, a longtime receptionist at the school.

Another person is still unaccounted for, seven were initially admitted to Hennepin County Medical Center with injuries. HCMC tweeted at 4 p.m. that they are currently treating four people -- one is critical and three are in satisfactory condition.

HCMC has confirmed that the person in critical condition is Bryan Duffey. Minnehaha Academy's website lists Duffey as an assistant coach for the boys soccer team.

Five others have been discharged, they say.

The person who is unaccounted for is presumed to be under the rubble, according to Fruetel.

Fruetel said both the victim found dead and the one missing are staff members at the school.

According to family members who talked to KARE 11, John Carlson, an 81-year-old custodian, is still missing and no one has been able to reach him.

The school has confirmed he is the man who authorities are still searching for in the rubble.

Because of hanging debris, Fruetel said they are working methodically to find the second person, while keeping their crews' safety a priority. He said they are hopeful it will be a rescue, not a recovery.

"It’s a very precarious situation," he said. "It’s very unstable. There are no signs of obvious location. We know there are two floors of debris. We still consider it a rescue at this point."

Earlier, it was stated that three people were reported as missing but one person was found around noon, uninjured.

The explosion happened around 10 a.m. at Minnehaha's Upper School on 3100 West River Parkway in Minneapolis. Officials suspect the explosion was caused when a contractor working on the building ruptured a gas line.

A work permit issued by the city of Minneapolis to an Eagan-based company, Master Mechanical Inc., allowed for gas piping and a meter hook up. Master Mechanical sent out a statement:

"Our thoughts and prayers are with everyone involved in this tragedy and especially with the families and loved ones of those who have died or who have been injured.

We are forever grateful to those first responders and bystanders who came to the aid of all of the injured, including our employees.

We continue to monitor the situation and are working in full cooperation with the Minneapolis Fire Department. At this time, we are referring all questions about the event to the Minneapolis Fire Department out of respect for their continued efforts.”

"It is a good thing that it is summertime," Asst. Fire Chief Bryan Tyner said. "Probably limited the amount of people in the building."Philip Day, who was with his daughter in the building, said a staff member ran up to them and told them they needed to evacuate immediately. "Seconds after that ... my daughter got up and was getting ready to leave out of the counselor's office and was blown back into the counselor's office by the explosion," he said. "I mean, it was seconds after they told us to get out that the explosion happened."

Day said before they knew it, they were surrounded by debris. "All the windows in the office blew out, rubble from the ceiling came tumbling down," he said. The counselor they were meeting with, Kristin Overton -- who is 7 months pregnant -- jumped over her desk and took cover, when the windows shattered and the ceiling came down. She said the explosion was instantaneous with their warning to evacuate. Day said the Minnehaha Academy community is very tight knit -- and obviously concerned about who may still be inside.

Those inside the gymnasium at the time say there was only a few seconds between someone saying they smelled gas and the building exploding. "As soon as they said, 'Hey, we smell gas, we gotta get out,' it exploded," said Tramon Vanlear, who was inside the gym. "I think the magnitude is the biggest thing I'm trying to comprehend right now."

A basketball team and a soccer team were practicing at Minnehaha at the time of the explosion. Charlie Peterson was actually interviewing for a job at the school -- then ended up being one of three people rescued from the school's roof. "I got under the conference table and the ceiling came down and we got out the windows onto the roof and about 15 minutes later, they got ladders up to us," he said. Residents near the area say they could feel the explosion. Some say their power flickered briefly afterwards.

"It was just a really loud boom," said one resident. "You felt it in your chest." Dr. James Miner, chief of Emergency Medicine for HCMC, said during a news conference that this is something the hospital trains for and they were well prepared for the aftermath of Wednesday's explosion. He said there is also medical staff at the scene.

A prayer service will be held at 7 p.m. at the school's lower and middle school, at 4200 West River Parkway. The school lists multiple summer programs currently in session including woodworking, intermediate band, advanced band and driver's education.

Gov. Mark Dayton issued a statement after being briefed on the incident. “My office is in continuous contact with the City of Minneapolis and the Minnesota Department of Public Safety, as emergency personnel respond to this emergency. The State will provide any and all resources necessary to aid first responders in their efforts to ensure the safety of all those impacted by this morning’s explosion. 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.”

Minnehaha Academy, a private school in Minneapolis, was built in 1912 and welcomed its first students in 1913. The South Campus was purchased and a chapel was erected in 1981. The Upper School currently serves grades 9-12, while the lower and middle school, 4200 West River Parkway, serves students from PreK to 8th grade. The school integrates faith and learning, through Bible study, chapel services and guidance from a Christian faculty and staff. "Today, the school remains dedicated to the Christian ministry set forth by its founders," according to the school's website. "This private, Christian school sponsored by by the Northwest Conference of the Evangelical Covenant church, serves approximately 900 students from the Twin Cities area."