The Ormond Beach Generating Station jolted slumbering residents of Oxnard and Port Hueneme early Wednesday and Thursday with a loud noise some described as explosions or jet engines.

Tom Di Ciolli, the station’s plant manager, said an emergency relief valve released steam from a pressurized boiler around 4:30 a.m. on Wednesday. The same boiler shot out steam at about 1 a.m. and 7:30 a.m. Thursday, he said. 

The power plant shut down the faulty unit Thursday morning, and plant employees are currently working on it, Di Ciolli said.

The emergency relief valves don't activate often, but when they do, the noise isn't typically heard by residents, Di Ciolli said. Because the valve released steam in the morning, the sound was heard in neighboring communities. 

Locals speculated wildly about the source of the sound – from natural disaster to jet engines to invasion.

Jackie Guzman, of South Oxnard, said in a text message she woke up Wednesday to what she thought was the sound of rain. When she looked out the window and didn’t see water, her mind began to race. 

“I started thinking it was a tsunami, and it was getting closer,” Guzman said. “Since I was half asleep, so many conclusions of what this sound could be was racing through my head, because then I started thinking we were getting bombed.”

In Port Hueneme, Peter Wearing said he woke up Wednesday to a noise he described as the constant droning of a jet engine being worked on.

“I mean, it was loud,” Wearing said. “I couldn’t sleep, and I’m one of those people who sleep quite soundly.”

Even after he closed his windows, the sound still prevented him from falling back to sleep. 

Port Hueneme Mayor Richard W. Rollins said he slept through the Wednesday morning noise, but residents didn't.

He said he received about eight to 10 calls Wednesday morning. Some thought noise was coming from SpaceX, Elon Musk's spacecraft manufacturing company. Others thought Oxnard's paper mill was the source of the noise. 

Oxnard Councilwoman Gabriela Basua, whose district includes the power plant, said she also never heard a thing. However, she woke up to three text messages from residents wondering about the noise. 

"I think it was a definite fright for a lot of people," she said.

The Port Hueneme Police Department received about 30 phone calls from residents asking about the noise Wednesday, city spokesperson Scott Matalon said. By Thursday afternoon, that number had increased to over 100, according to a social media post.

The Oxnard Police Department received about 200 phone calls Wednesday morning by residents awoken by the noise, according to city spokesperson Katie Casey. The department received at least another 30 calls Thursday and Friday mornings, police Cmdr. Luis McArthur said.

Residents reported to authorities and on social media hearing the loud noise outside the pressure release times confirmed by the plant. One call came in Thursday at 4:30 a.m. from the Riverpark neighborhood, McArthur said.

Di Ciolli said he wasn’t aware of any other pressure releases but couldn’t rule out the possibility. 

Brian J. Varela covers Oxnard, Port Hueneme and Camarillo. He can be reached at brian.varela@vcstar.com or 805-477-8014. You can also find him on Twitter @BrianVarela805.