The sheriff's office served eight search warrants in connection with auto burglaries, attempted vehicle thefts and other crimes that occurred at Lake Berryessa on July 7, sheriff's Capt. Tracey Stuart said.
Five of the warrants were served in Vallejo, two in Benicia and one in Walnut Creek, Stuart said.
Stuart said the grenade was found in a residence at 203 Mobile Lane in Vallejo, in the Newell Mobile Home Park.
A resident of the mobile home park said part of the park was evacuated Wednesday morning.
Stuart said arrests have been made in connection with the Lake Berryessa crimes, and that more details will be released this afternoon.