MINNEAPOLIS (AP) — Two people are unaccounted for after an explosion and partial building collapse Wednesday at a private college prep school in Minneapolis, fire officials said.

The Minneapolis Fire Department said the explosion was reported at Minnehaha Academy, a Christian school serving students from pre-kindergarten through 12th grade. The agency initially said three people were missing, but later said one of those people had been found uninjured.

Police said five people were taken to a hospital with injuries, though one has since been released.

Assistant Fire Chief Bryan Tyner said three people were rescued from the roof. He said crews were working to put out a fire in the building and searching for the missing individuals who may be trapped in the rubble. He didn't immediately know whether the missing were adults or children.

Tyner said it appears the explosion may have been caused by a ruptured gas line, but that the investigation is ongoing.

Minnehaha Academy is on summer break, but many students and staff were at the campus for basketball practice, soccer and cross country activities.

The school has multiple buildings. In a post on its Facebook page, the school said the explosion only affected the "upper school," and staff inside the building reported hearing a loud noise and feeling the building shake. The academy's lower school was unaffected.

Tramon Vanleer, who helps coach a summer program, was in the gym when the explosion occurred. He told KARE-TV that he had five girls with him when the explosion happened.

"It sounded like a freight door shutting. It sounded like a large door shutting, and at the same time the lights went out and there was some debris that fell from the ceiling, so we just got out as fast as possible," he said. "It didn't sound that bad on the inside of the gym, but coming outside it was a lot worse."

About a dozen students who were in upper school gym but all are OK, according to Sara Jacobson, executive director of institutional advancement at the school.

City records show that Eagan-based Master Mechanical Inc. was issued a permit on June 7 for "gas piping and hooking up meter" at the address. Ryan Larsen, a financial officer with the company, told the Star Tribune: "We've got people on the site there. They are figuring it out."

Gov. Mark Dayton released a statement saying his office is in continuous contact with city officials about the situation. Dayton said the state "will provide any and all resources necessary" to help first responders and ensure everyone is safe.

The Minneapolis Fire Department initially tweeted that one fatality was reported, but Tyner later said that fire officials were backing off that statement.