PORTLAND, Ore. (AP) — Officials say the Oregon State Police is investigating three Oregon Department of Transportation employees on theft allegations. The Oregonian/OregonLive reports three employees from the Lawnfield Maintenance Station in Clackamas are being investigated. Two of them, John Tipton and Autumn Arndt, have submitted letters of resignation. A third, Frank Smead, has been placed on unpaid administrative leave. Agency spokesman Tom Fuller said he couldn’t go into specific details about the allegations, but characterized them as “very serious,” and said the gravity of the accusations referred to the amount the three had allegedly stolen. He said investigators believe the three acted together.