Construction workers struck a service line while working on Sensenbrenner Hall Wednesday causing a gas leak in Johnston Hall.

Students and faculty evacuated Johnston Hall around 12 p.m. and were not allowed re-entry for more than an hour, forcing many students and faculty members to relocate to the Law Library, Straz and Cudahy halls. The Department of Public Safety, Milwaukee Fire Department and Police Department sealed off the area around Johnston Hall until it was reopened around 1:30 p.m.

“As precaution, we evacuated all those students and employees in Johnston,” said Brian Dorrington, senior director of university communication. “We were informed both by DPS and MPD there was a potential gas leak from construction on the site.”

We Energies arrived at the scene to repair the service line, which was finished by 3 p.m. We Energies spokesman Brian Manthey noted that the repairs and situation would have been different if a main gas line was struck instead of just the service line.

“The service line leads to the main (line) of a particular building,” Manthey said. “If it hit a main, we might have needed to shut off the gas.”

Carole Burns, director of the Wakerly Technology Training Center, said she saw the line get struck just before smelling the gas.

“All of a sudden it started being a pretty heavy smell of natural gas in the building, so we called public safety, and they suggested that we evacuate until further notice,” Burns said shortly after evacuating.

Dorrington said the evacuation, which lasted less than two hours before classes resumed, ended once it was determined safe to re-enter.

“We assessed the situation, and it was within an hour that we got the all clear,” Dorrington said. “The fire department, along with We Energies, determined that there was no safety risk.”

The Wehr Chemistry building was evacuated in March for a chemical leak, but began activity again just two hours later. In that case, both DPS and the Environmental Health and Safety verified that the chemical released was harmless.