Miami-Dade rushed police to understaffed storm shelters on Friday after delays in opening about two dozen facilities, with Mayor Carlos Gimenez describing a plan overwhelmed by the largest evacuation in the county’s history.

The police deployments, announced Friday evening, followed a hectic day of shelters stopping people at the door because they were full or not ready to open yet. It was after dark when Gimenez announced the long-awaited names of two dozen new shelters ready to accept new residents. By 8 p.m., more than 40 shelters were listed as open, with six at capacity, and about 23,000 people inside of them.

“There were some glitches,” Gimenez said. “We’re human. and sometimes we make mistakes. But we’re going to learn from these mistakes.”

(For a list of which shelters are open and which shelters are filled in Miami-Dade County, click here or see box at the end of this story.)

The central problem appeared to be the gap between the number of shelters Miami-Dade wanted with the staffing available to manage those shelters. The county said it had counted on a combination of Red Cross and National Guard personnel to run more than 40 shelters, which are mostly housed in schools.

Despite its ambitions, Miami-Dade began Friday with only eight shelters operating and four of them were full by mid-morning. In the race to open others, school administrators said they stepped in to run operations that should fall under the county government’s responsibility during storms. That saw some principals coming in to oversee shelter operations and what was generally described as a rocky effort to keep ahead of demand for refuge from Hurricane Irma.

“I cannot underscore enough the need for a faster deployment of the management entities to the shelters after the opening time is declared,” schools chief Alberto Carvalho said Friday afternoon. He said he had made the executive decision to allow evacuees to enter school sites at the declared opening time even if county officials had not yet arrived, and that he would continue to do so.

At an evening briefing, Gimenez acknowledged a string of challenges with the shelter operations, including a computer system that left some administrators in the dark about shelter capacity and enough confusion about what do when a shelter got full that county bus drivers were commandeered to take people to unauthorized locations.

With the National Guard arrivals scheduled for midnight Friday and the Red Cross described as maxed out on volunteers, Gimenez dispatched dozens of police officers to schools across the county to help guide arrivals, supervise operations and other tasks.

“It’s all hands on deck,” said Juan Perez, director of Miami-Dade’s police department. “We’re willing to step in and fill the void.”

Even though some were full, most shelters on Friday were still able to accept residents. Gimenez said he wanted shelter spaces for 100,000 people to match an unprecedented evacuation effort he ordered ahead of a Category 5 storm menacing Miami. His voluntary evacuation orders issued Wednesday and Thursday covered more than 600,000 people.

By Friday afternoon, only 21 shelters were listed as open, and it was clear the county was struggling to keep on schedule.

“People are coming in droves,” said Dennis Moss, a Miami-Dade commissioner representing South Dade who told the media about the Robert Morgan Education Center in southwest Miami-Dade being filled to capacity about an hour before the county could confirm the information. “People don’t feel safe in the housing they’re in.”

Earlier in the day, Gimenez acknowledged the strain in trying to open the most shelters in Miami-Dade’s history, on the heels of an evacuation order covering more than 600,000 people. “Opening a shelter is not as easy as you think,” he said at a midday press briefing. “We’ve run out of Red Cross volunteers. Now we’re going to use the National Guard.”

The county faced push back on its explanation. A Red Cross spokesman denied the charity had fell short of volunteers. The state, which oversees the National Guard, said it is up to the county to get the shelters open.

Bryan Koon, director of the Florida Emergency Operations Center, said it is the county’s role to open shelters but they don’t need to be stocked with all the supplies in order to open.

“It is not vital that all of those things be in place. The vital thing is they are in a hardened storm shelter and they will live,” he said. “By having the shelters open, they are given the motivation to leave and be safe.”

William Manley, spokesman for the Florida National Guard, said the agency mobilized 7,000 soldiers to face Irma’s broad threat to the state. “They’re sprinkled everywhere,” he said. A storm threatening all of Florida has caused staffing complications, Manley said, but he noted local agencies can also staff shelters if the National Guard isn’t available.

With tropical-storm force winds expected sometime Saturday, the nighttime openings of more than 20 shelters staffed by police officers offered more last-minute options for people deciding to leave their homes ahead of Irma. Gimenez said he expected a rush Saturday morning, and wanted the county to err on the side of providing too much shelter.

“I’d rather have 80,000 empty spaces, than have people turned away because we have no more room in shelters,’ he said. “This is an extremely powerful storm that poses a great threat to Miami-Dade County.”