Investigators are calling the fire accidental. the blazed ignited a diesel line, which caused black smoke and an awful smell inside the hospital.
"It smelt like a gas, or some kind of chemical smell and we started getting a little light headed," said Delia Handy, a mother of a patient.
People prepping for surgery were forced to evacuate the building.
"We were on the second floor and she was getting her gown and stuff on. We were getting ready, prepared and all that stuff and then the fire alarms went off," Handy said.
#HospitalIC fire in boiler room under control. Significant smoke on second floor— Confire PIO (@ContraCostaFire) October 7, 2016
Fire filled a boiler room in the middle of the hospital at around 2 p.m. Friday.
"You're always worried about the smoke and in this particular case it was a fuel fed fire, meaning that the boilers themselves are powered by natural gas and diesel fuel," said Contra Costa County fire Marshal Robert Marshall.
"We had two patients in the operating room. They were able to complete the surgeries safely and effectively. Those patients were recovered on the third floor, instead of the second floor," said Martinez Health Center Dr. Shamir Shah.
As firefighters extinguished the flames nine surgery patients were evacuated off the second floor into safer areas of the hospital. The fire Marshal says the building is constructed for emergencies.
"Those smoke and fire barriers are designed to hold a fire at bay for up to two hours," Marshall said.
The hospital closed to emergency patients for more than four hours and diverted ambulances to facilities in Concord. Once PG&E restored gas service the hospital reopened. No one was injured.