PORT-AU-PRINCE, Haiti (AP) — Authorities in Haiti have arrested seven suspects, including five police officers, after a fatal stampede killed at least 25 people at a historic mountaintop fortress over the weekend, police said Monday.

Among the arrested are two employees of Haiti’s Institute for the Preservation of National Heritage, which oversees La Citadelle, an imposing fortress in the northern town of Milot built in the early 1800s where Saturday’s stampede occurred.

Dozens of people were injured, with 30 reported to still be in hospital on Sunday. It’s not clear what caused the stampede. A police investigation is ongoing.

It wasn’t immediately clear if the police officers or institute employees have been formally charged.

Milot Mayor Wesner Joseph told Magik9 radio station on Monday that his administration was not aware of any activity planned at La Citadelle on Saturday, and that authorities later found that a local DJ had invited people there for an event via TikTok, with many children and teenagers attending.

Ahead of the event, videos posted on social media show hundreds of young people making the arduous, roughly 8-kilometer (5-mile) hike up a steep mountain to reach La Citadelle, while some opted to ride horses.

Another video shows two young Haitians driving around promoting the event via loudspeakers, more than a week before it was held: “You have to hurry to make sure you’re in the line.”

The event, for which participants had to pay nearly $8 to attend, promised free water and fruit juice, with promoters urging attendees to meet at 7 a.m. at the park below La Citadelle and noting everyone should be present by 10 a.m.