Authorities in Haiti have arrested seven suspects, including five police officers, after a fatal stampede at La Citadelle in the northern town of Milot killed at least 25 people, police said Monday.

Police said dozens of people were injured in the weekend crush, and they said 30 of the injured were still receiving hospital care on Sunday. Authorities have not said publicly what caused the stampede, and they said a police investigation is ongoing.

Among those arrested were two employees of Haiti’s Institute for the Preservation of National Heritage, which oversees La Citadelle, an imposing mountaintop fortress built in the early 1800s. Police did not immediately say whether any of the suspects had been formally charged.

Milot Mayor Wesner Joseph told Magik9 radio station Monday that his administration had not been aware of any activity planned at La Citadelle on Saturday. Joseph said authorities later learned that a local DJ had invited people to the event via TikTok, and that many children and teenagers attended.

Ahead of the stampede, videos posted on social media showed hundreds of young people making the arduous hike up the steep mountain to reach La Citadelle. The hike is about 8 kilometers (5 miles), and some people instead opted to ride horses, according to the videos described by police.

Other videos showed two young Haitians driving around to promote the event with loudspeakers more than a week before it was held. One of the organizers urged people: “You have to hurry to make sure you’re in the line.”

Police said participants had to pay nearly $8 to attend. Organizers also promised free water and fruit juice, and promoters urged attendees to meet at 7 a.m. at the park below La Citadelle, saying everyone should be present by 10 a.m.