LINCOLN, Neb. (AP) — Authorities say a man suspected of setting off an explosive device in a Lincoln park has been arrested after nearly two dozen more devices were discovered in his home.

Witnesses at Tierra Park say the man set off the device around 11:30 a.m. Tuesday and then went to the house. No injuries have been reported, although several dozen schoolchildren were at the park on a field trip.

Police say they obtained a search warrant and then found 21 more improvised explosive devices that they don’t think were fashioned at the home. Authorities are trying to determine whether the man is connected to mailbox bombings around the city.

Online court records don’t show that the man has been charged.