Walt Disney Co is also ending sales of toy guns at its parks, banning visitors over the age of 14 from wearing costumes and adding randomized secondary screenings of visitors with metal detectors.
Guests at Disney theme parks in Anaheim, California, and Orlando, Florida, previously had their bags checked by hand and with a handheld metal detector, officials said.
The moves follow a Dec. 2 shooting rampage that killed 14 people in San Bernardino, California, by a married couple inspired by Islamic State and Nov. 13 attacks in Paris in which 130 people died.
The theme park companies did not refer to either event in announcing the increased security, although Disney did say it was increasing security in light of recent events. Anaheim is about 50 miles (80 km) southwest of San Bernardino.
SeaWorld Entertainment Inc is also using metal detectors at its Orlando park, according to local media reports.