On July 22, local time, a shooting occurred in Marquakta Caves State Park in Iowa, USA, killing four people, including the suspect with the gun.

  Mike Krapfl, head of the Iowa Bureau of Criminal Investigation, said at a news conference that the park was closed and the shooting posed no threat to the public.

Police are still investigating the case, and the relationship between the four dead remains unclear.

(CCTV reporter Xu Dezhi)