Visitors to the state's vaccine appointment website were greeted Thursday by an error message featuring a confused-looking orange octopus. Screenshot | State House News Service

As about 1 million more people became eligible for the COVID-19 vaccine Thursday morning, the state-run website that people must use to find and book most appointments has crashed and does not appear to allow residents to schedule vaccinations.

The state’s COVID-19 Command Center was not immediately available to provide details, but people visiting the vaxfinder.mass.gov website after 8 a.m. Thursday were met with a message that “this application crashed.” Visitors were advised to try again later.

“Due to high volume, vaxfinder.mass.gov is currently experiencing technical difficulties. Appointments at mass vaccination locations have not yet been posted today, but will be made available soon. More updates to follow,” the official state government Twitter account posted around 8:45 a.m.

When Gov. Charlie Baker announced Wednesday that people 65 years old or older, the residents and staff of affordable and low-income housing for seniors, and people with two or more health conditions that put them at higher risk for hospitalization or death would be able to start booking vaccination appointments at 8 a.m. Thursday, it represented a doubling of the number of people currently eligible for the limited number of vaccine doses.

In a state with a population of about 6.9 million, about 1.1 million people were eligible for vaccines Wednesday, and approximately another million joined them today.

The interest was immediate. When word of the governor’s announcement got out before his press conference, the website saw about 250,000 visits.

Baker said Wednesday that he thinks the vaccination appointment website “will be in good shape” for the added traffic Thursday morning, and did not address the issue during a morning address to the Greater Boston Chamber of Commerce.

Even before Thursday’s website crash, discontent with Baker’s handling of the vaccine rollout has been growing. The legislature’s new COVID-19 and Emergency Preparedness and Management Committee will host a hearing on Feb. 25 to hear testimony from the executive branch about how it has been distributing vaccine doses and its plans for the future, legislative leaders said.

House Speaker Ron Mariano and Senate President Karen Spilka criticized the administration’s approach as they unveiled their plans to get more involved. Mariano said the rollout “has been marked by both logistical and communications shortcomings” and Spilka called it a “constantly changing and confusing” plan.

Hearings will be led by state Sen. Jo Comerford, a Northampton Democrat, and state Rep. Bill Driscoll, a Milton Democrat, who are chairing the COVID-19 and emergency management panel.

“The Commonwealth seems to have been underprepared for the complexities in Phase One of the vaccine rollout,” Driscoll said in a statement. “We all understand that patience is paramount in our current pandemic circumstances, but patience and public trust wear thin when there are constant pivots in the plan.”