The Oakland Arena closed its gates due to an unspecified problem Thursday night, leaving concert-goers stranded outside for hours and generating standstill traffic.

At 8:21 p.m., 20 minutes after German composer Hans Zimmer’s concert was scheduled to start, the arena posted on X that it was “experiencing a delay.”

Some frustrated fans on social media said Oakland police were not allowing anyone inside the arena, and anyone already inside was not allowed out. “They’re not letting people in or out and aren’t informing anyone on what’s going on or what will happen,” one person said.

The closed parking gates generated major traffic in the area. Some concert-goers stuck in traffic on the Interstate I-880 off-ramp by 66th Street exited their cars and began trekking on foot to the concert venue, according to a Chronicle staffer who observed the scene.

The arena’s parking and entry gates reopened just before 9:30 p.m. and the show was scheduled to start “as soon as possible,” the arena wrote on X.

Alexandra McVeigh and Alana MacDonald, both 31, said they had been trapped outside the arena since arriving at 7:30 p.m. with minimal explanation from arena officials. Every 10 minutes or so, officials said the gates had been closed due to a “safety concern” and would be opening “as soon as possible” but provided no other information, McVeigh said.

“There’s absolutely no movement,” said McVeigh, an Oakland resident who had hoped to attend the concert as an early birthday celebration.

The rest of McVeigh’s party made it into the arena before the gates closed, but received no explanations from officials inside and were not allowed to exit, she said.

Some concert goers waited in line for over an hour to have their tickets scanned, before giving up and returning to their cars, MacDonald said.

By the time the gates reopened just before 9:30 p.m., some attendees had already left the scene, according to social media posts.

Hans Zimmer is a German film score composer best known for his music in movies like Interstellar, The Dark Knight Rises, and Dune. His “Hans Zimmer Live” tour, played alongside a live band and orchestra, has been touring North America since the beginning of September.

Zimmer is scheduled to play a second show at the Oakland Arena on Oct. 9, according to the musician’s website.

Oakland Arena officials did not immediately respond to a request for information. Easily Upload Images