Sun Prairie Fire Chief Chris Garrison said at a news conference that after the leak was initially reported at 6:20 PM CDT, first responders established a 300-ft-dia "hot zone" in the area and evacuated about 65 people before the explosion occurred. Teams of two firefighters each went into area buildings to shut off the gas. Barr and Firefighter Ryan Welch were leaving the Barr House when the building exploded approximately 40 minutes after the initial leak was identified. Welch suffered burns to his face, a broken jaw, lost teeth and injuries to both hands after the building came down on both men. Welch has since been released from the hospital.

"The rapid response of firefighters, EMS and police saved a lot of lives," Garrison said. "This could have been a lot more tragic than it was." He said about 200 firefighters and 50 law enforcement personnel assisted with the evacuation.

Lt. Kevin Konopacki, a Sun Prairie Police Dept. spokesman, would not say whether the city is investigating the incident as a criminal matter and said his department's investigation is "still a very active death investigation" at a July 16 press conference. State law requires notice of digging to be placed no fewer than three days before starting work, unless there are emergency circumstances. Under a recently passed law, violations of the digging rules are reviewed by the state Public Service Commission and could result in $25,000 in fines per offense, among other penalties. Chad Krueger, manager of public relations for Diggers Hotline Inc. of New Berlin, Wis., said the company would not release information about private requests for location information from customers.

The line-laying work was being performed for Bear Communications, Lawrence, Kan. Scott Stein, a spokesman, confirmed in a statement that one of its subcontractors, VC Tech, Inc. of Ypsilanti, Mich., was working at the site of the leak, but added that "Bear Communications continues to cooperate fully with all parties involved in the investigation of the explosion that took place Tuesday in Sun Prairie. Bear Communications was building a fiber network in the Madison area. As is common on projects like this, Bear Communications subcontracted out certain scopes of work. VC Tech was working in the area prior to the blast, and when VC Tech’s employees smelled gas they notified authorities of the gas leak and assisted in evacuating people from the area before the explosion occurred. No one from Bear Communications was present on site when the gas line began leaking."

Amy Jahns, a spokeswoman for the gas line owner, WE Energies, would not comment on whether anyone had contacted it to identify the location of the gas line before starting work, but she did say someone punctured a 4-in. gas main, causing the leak that eventually resulted in the explosion. She said WE workers who arrived on site after the breach were not able to contain the leak at its source.

The owner of the fiber-optics network is Verizon Wireless, which confirmed in a statement that it had contracted with Bear Communications "to provide a fiber backhaul for our networks." It added that no Verizon employees were present at the job site. "Verizon does contract with local providers in various markets to provide fiber backhaul for our networks," the Verizon statement said. "While we have not been contacted about the investigation, both we and Bear are prepared to work with law enforcement, public safety and public officials as they investigate this tragic situation." 

A spokesperson for VC Tech declined comment citing the pending investigation.

According to the U.S. Census Bureau, Sun Prairie, located about 14 miles northeast of Madison, had a population of 32,829 in 2016.