MINNEHAHA COUNTY, S.D. (KSFY) - Authorities say they are investigating a string of explosions in Minnehaha County.
According to Sgt. Josh Phillips with the Minnehaha County Sheriff's Office, a deputy doing a routine check around 10 p.m. at Baltic River Park on Aug. 10 witnessed an explosion.
A plastic sign that stated fishing hours for the park was blown up. The deputy did not see any suspicious people in the area.
Campers at Baltic River Park reported another explosion around 10:18 p.m. on Aug. 11. Nothing was found destroyed.
The explosions were described as very loud with white and blue lights.
Two mailboxes also exploded in Sioux Falls near some railroad tracks on East Rice Street around 7 a.m. on Aug. 12. Authorities found what they thought were homemade fireworks at the scene.
On Aug. 13 around midnight, a man in rural Rock County, Minnesota, also reported his mailbox had exploded.
Back in Minnehaha County, two other mailboxes were also blown up in rural Garretson and Valley Springs over the weekend.
The sheriff's office is working with the Sioux Falls Police Department, ATF and Postal Service.
No one was hurt in any of the explosions, and there are no suspects at this time.
Authorities are asking for the public's help. Anyone with information about the explosions is asked to call Crime Stoppers at 877-367-7007.