Around 2:30 p.m. the building, on Old Redwood Highway in Santa Rosa was full of patients and employees like Registered Nurse Nannette Henning.
"What we felt was the building shook," she said. "My very first thought is, 'Oh my God. It's a terrorist attack.' No one knew what was going on but everyone remained really calm and we just reassured the patients that we needed to get out of the building."
Santa Rosa Assistant Fire Marshall Paul Lowenthal says the explosion caused a small brush fire and a worrisome gas leak, so authorities shut down Highway 101 in both directions ad evacuated two Kaiser offices while the department's hazmat team secured the majority of the leak.
VIDEO: SKY7 over oxygen truck crash, highway closure in Santa Rosa
"We kept getting pushed farther away from the building," said Kaiser physical therapist Kathy Larson.
Larson works in the back of the building near the oxygen tanks. She says evacuating the patients was challenging. "In this building, there is outpatient surgery so there was people who were recovering from surgery. There were people on IVs hooked up to IVs still, some people in beds."
Larson and Henning both said that evacuating was an all-too-soon reminder of the North Bay Fires and the evacuating of the Kaiser Medical Center down the road.
"Here we go again with this big event," Larson added.
"It was rattling for a lot of us to have to have been evacuated before and then go through this again," said Henning.
CLOSURE INFORMATION: 3975 Old Redwood Highway (MOB 5) will continue to be closed on Friday, July 20, pending concluding regulatory and fire inspections and testing, and removal of the tanker. Kaiser Permanente is reaching out to patients who have scheduled appointments or ambulatory surgery on Friday, July 20, to reschedule and make alternative arrangements.
*Hazmat Kaiser Hospital* Santa Rosa Fire and Police along with AMR and CHP are at scene of a hazmat incident involving a oxygen tanker truck. Kaiser Old Redwood Hwy campus is evacuated. Hwy 101 and Old Redwood Hwy are both closed in both directions in the immediate area.— Santa Rosa Fire Department (@SantaRosaFire) July 18, 2018