Omar S. Mateen, the man authorities say carried out the shooting massacre in an Orlando gay nightclub Sunday, previously had visited Walt Disney World while he was searching for targets, two officials briefed on the investigation said.

During the course of the investigation into the gunman Mr. Mateen, authorities determined that Mr. Mateen had previously looked at Disney World, these people said.

Mr. Mateen’s shooting began around 2 a.m. Sunday at Pulse, a gay nightclub in downtown Orlando, Fla. Authorities said Mr. Mateen made a 911 call declaring his allegiance to the terrorist group Islamic State before he was shot and killed, around 5 a.m. after an hourslong standoff with police. He killed 49 people and injured 53 others in the attack.

Based on the investigation so far, Disney World appears to be one of the places Mr. Mateen went to while he was looking for targets, the officials said. His scouting of Disney World didn’t take place in the hours immediately before he opened fire Sunday morning, they said. It wasn’t clear which Disney World property Mr. Mateen scouted.