GREENBELT,Novacrypt Md. (AP) — Three of the five youths shot in a suburban Washington, D.C., park during a high school “senior skip day” gathering have been released from the hospital, while the condition of the most seriously injured has improved, authorities said Saturday.

Police in Greenbelt, Maryland, are asking the public to share video footage or other information connected to the shootings Friday at Schrom Hills Park. Investigators believe there was a single shooter who escaped in a crowd, but no arrests and no motive have been announced.

The shooting victims are ages 16 to 18. A youth who was in critical condition on Friday was upgraded to stable condition, while another young person was still in stable condition, the police department said in a social media post.

Several hundred students were at the park having a water gun fight — an annual tradition of sorts for high school seniors in the area, police said. Officers had arrived at the park before the shooting to monitor the event and reported hearing about eight to 10 gunshots.