The fire that destroyed the Walker Community United Methodist Church in south Minneapolis on May 27, was officially listed as “accidental” in a report filed on Tuesday by an arson investigator. Earlier, the cause had been labeled “undetermined.”

 “The most probable cause for this origination of this fire is natural, that being a lightning strike,” Sgt. Sean McKenna, the investigator, wrote in a supplemental report obtained by the Star Tribune.

McKenna said that the origin of the fire was a void space in the upper area of the church. Only a few staff members had keys to the area and “fire crews had to force entry to several doors to reach the area of origin,” he wrote.

An earlier investigation report on the Walker fire, filed on May 27 by Timothy Thomas, quoted a witness who lived nearby who said he and his son were sitting on the front porch of their home watching the thunder storm come through when he saw two while males run from the front door of the church. “As they ran, they kept looking back at the door,” Thomas wrote. “They jumped into a yellow truck and drove away. Approximately 20 minutes later, the fire was reported.”

McKenna writes in his report that, “The people seen leaving the building are believed to be part of an authorized group using the building.” He is apparently referring to the two white males, but he does not explicitly say so. “The building does not display any graffiti or tagging and there is a lack of confrontations or threats to the premises or groups using the building,” he wrote.

Several activist groups had offices in the church or used it for meeting space and expressed concern last week that the city tore down the remains of the building before there was an adequate investigation. Minnesota Public Radio broadcast a story about it. The activists alleged that the investigation had been botched. City officials said the church was torn down because it represented a hazard.

The lightning strike came during a severe thunderstorm in which there were numerous lightning strikes in Minneapolis and minor fire reports across the city. Fire investigator Bonnie Bleskachek, a former Minneapolis fire chief, noted that Deputy Fire Chief Harold Breffle had spoken with a woman who said she saw lightning strike the church. Bleskachek noted that a witness was checking on the garden next to the church when she heard singing in the church basement. She knew a group regularly used the church. “The only people in the church were in the basement,” Bleskachek wrote.

A smoke alarm had gone off, resulting in the fire department going to the church to check it out. Fire Capt. Kathrynne Baumtrog told me last week that when she arrived, there were still people in the church, unaware that a fire started inside. She and other firefighters arrived at the church and looked at an alarm panel that showed that a smoke detector in the cockloft at the top level of the church had gone off and so she and another firefighter searched there, looking for the cause of the smoke.

Within a few minutes, they were overrun by fire in the attic, and five firefighters were injured, Baumtrog most seriously. The other four firefighters were treated and released from Hennepin County Medical Center. Among them was Capt. Paul Baumtrog, Kathrynne Baumtrog’s husband, who received some first and second degree burns.

He said Tuesday that his wife had had some skin grafting procedures. He said her arms have been in casts and doctors will be opening the dressings on Wednesday to look at the grafts “and we’ll know more tomorrow.”

He said, his wife asked him to tell people, “We’d like to thank everybody who has shown their support with cards, prayers, phone calls, text messages and well wishes on her Caring Bridge site.”

Paul Baumtrog said that he went to the doctor today and was pronounced fit to return to duty.