ORLANDO, Fla. — Walt Disney World and Universal Orlando are hiring additional security employees as theme parks enter what experts say is a new era of stepped-up efforts to shield visitors from possible terrorism.

The parks would not say how many people they are adding or give details on the measures they are taking. At Disney, many of the new security personnel will help staff metal detectors. A third-party company has overseen the detectors since Disney — along with the two other major parks — put them up last month. Over the coming weeks, Disney is moving the operation in-house.

One expert said the number of new security hires would likely be large.

“I would say given the nature of their operation, we’re not talking about tens. We’re talking about hundreds,” said Abraham Pizam, dean of the University of Central Florida’s Rosen College of Hospitality Management.

In the wake of attacks in Paris and San Bernardino, Calif., attractions are focusing more on security, said Dennis Speigel, president of the consulting firm International Theme Park Services.

“I think in 2016, we’re going to see the implementation of more security measures, heightened security, than we’ve seen in the last three decades,” he said.

Last month Disney made several security changes, including forbidding costumes on adults in the theme parks and banning toy gun sales. As it announced those restrictions Dec. 17, Disney — along with SeaWorld and Universal — began using metal detectors at its gates.

Universal describes its detectors as in an experimental phase.

“We really wanted to test what we see as best practices when it comes to security,” spokesman Tom Schroder said.