MECHANIC FALLS (AP) — Authorities said the investigation into a Maine hayride accident that killed a 17-year-old girl and injured more than 20 others could be finished by the end of the week.

Investigators said it appears a mechanical problem caused a Jeep towing a wagon full of passengers in Mechanic Falls to crash during a Halloween-themed hayride at Harvest Hills Farm on Saturday. Oakland resident Cassidy Charette died from head injuries as a result of the crash.

Maine Fire Marshal’s Office Sgt. Joel Davis said Tuesday that the inspection of the vehicle will be finished later this week. He said the amount of weight carried by the Jeep will also be an “important factor” in the investigation’s conclusion.

Maine officials said the state doesn’t have statutes that regulate hayrides.