A day after announcing any adult could wait in line for a Johnson & Johnson shot at the mass vaccination site at Cal State L.A., the state said Thursday that “overwhelming demand” now meant people must make an appointment online — and those who had lined up were being turned away.

The California Governor’s Office of Emergency Services on Wednesday evening had announced that anyone older than 18 could walk up to get the single-dose COVID-19 vaccine, without making an appointment or meeting current eligibility restrictions based on age, occupation and health conditions.

Officials on site said they had had a surplus of vaccine due to thousands of unbooked appointments.

But when crowds of vaccine-seekers went Thursday morning to the campus in the El Sereno neighborhood of Los Angeles, many were turned away.

“They said, ‘make an appointment,'” Lizzy Dinnella said after waiting in line. “We’re not eligible to make appointments, so I’m not going to make an appointment. I’m not going to lie.

“I’m unclear if that means they’re running out. The information has been very sparse and confusing,” Dinnella added.

The Office of Emergency Services said in statement that the great demand — “driven by increased media coverage overnight” — meant no more walk-ups could be accommodated Thursday.

All adults will be eligible to be vaccinated in California in a week — on April 15. Right now, state guidelines in Los Angeles County allow for those 50 and older, some essential workers and those with certain health conditions to qualify for vaccination.

Asked about the situation late Thursday morning, a spokesperson for the Office of Emergency Services said the best way to get vaccinated at Cal State L.A. was to register for an appointment on the state’s MyTurn.ca.gov site — which requires one to answer questions that screen for county-based eligibility.

The office had said it might be possible for walk-up vaccinations to be given later in the day if some appointments remain unfilled, but that was apparently no longer the case within a couple of hours.

“Individuals currently waiting in line without appointments or those who want to be vaccinated at this site in the coming days should make an appointment through visiting the state’s MyTurn.ca.gov website or by calling 833-422-4255 prior to coming” to the campus, OES said in a statement tweeted out about 1:15 p.m. “The enthusiasm and interest from the public has been overwhelming and positive today and demand has far outnumbered the limited supply of 7,000 vaccines per day that we are able to administer.”

Meanwhile, some in line Thursday morning were handed cards with information about the MyTurn website, and some said they were able to make appointments online while still waiting. Others said they planned to keep their place in line in hope they would score a shot.

Some were disappointed, including one woman who drove from Lakewood and said she had worked up the “courage” to come up and get vaccinated.

“Someone got here 30 minutes after me and got through in another line — and they vaccinated them and they’re already on their way home. I’ve been here for two hours and they’re telling me they can’t take me now,” Rose Amadeus said.

The massive Cal State L.A. vaccine site, which opened in mid-February, has been co-managed by the Federal Emergency Management Agency and Cal OES. It will be taken over by the city of Los Angeles next week.

The site is open 9 a.m. to 7 p.m. on the campus at 5151 State University Drive, Los Angeles, CA 90032.